ultrix man page for link

link(2) 							System Calls Manual							   link(2)

Name
       link - link to a file

Syntax
       link(name1, name2)
       char *name1, *name2;

Description
       A hard link to name1 is created; the link has the name name2.  The name1 must exist.

       With  hard links, both name1 and name2 must be in the same file system.	Unless the caller is the superuser, name1 must not be a directory.
       Both the old and the new share equal access and rights to the underlying object.

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.

Diagnostics
       The system call fails and no link is created under the following conditions:

       [ENOTDIR]      A component of either path prefix is not a directory.

       [ENAMETOOLONG] A component of either pathname exceeded 255 characters, or the entire length of either pathname exceeded 1023 characters.

       [ENOENT]       A component of either path prefix does not exist.

       [ENOENT]       The file named by name1 does not exist.

       [ENOENT]       When name1 or name2 point to an empty string and the environment defined is POSIX or SYSTEM_FIVE.

       [EACCES]       A component of either path prefix denies search permission.

       [EACCES]       The requested link requires writing in a directory with a mode that denies write permission.

       [EEXIST]       The link named by name2 does exist.

       [EPERM]	      The file named by name1 is a directory, and the effective user ID is not that of superuser or  the  environment  defined	is
		      POSIX.

       [EXDEV]	      The link named by name2 and the file named by name1 are on different file systems.

       [EROFS]	      The requested link requires writing in a directory on a read-only file system.

       [EFAULT]       One of the pathnames specified is outside the process's allocated address space.

       [ELOOP]	      Too many symbolic links were encountered in translating one of the pathnames.

       [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.

       [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.

       [EIO]	      An I/O error occurred while reading from or writing to the file system to make the directory entry.

       [ESTALE]       The  file  handle  given	in the argument is invalid.  The file referred to by that file handle no longer exists or has been
		      revoked.

       [ETIMEDOUT]    A connect request or remote file operation failed because the connected party did not properly respond  after  a	period	of
		      time that is dependent on the communications protocol.

       [EMLINK]       The number of links to the file named by path1 would exceed {LINK_MAX}.

Environment
       In the POSIX environment, linking to directories is not allowed.

See Also
       symlink(2), unlink(2)

																	   link(2)