link

link

Create Link to File

Portability: POSIX.1 conforming, UNIX compatible

SYNOPSIS
DESCRIPTION
RETURN VALUE
EXAMPLE
RELATED FUNCTIONS
SEE ALSO

SYNOPSIS

#include <unistd.h>

int link(char *oldfile, char *newname);

DESCRIPTION

link creates a hard link to an existing USS file. oldfile is the existing file. If oldfile is a symbolic link, the link refers to the file that is referenced by the pathname in the symbolic link. newname is the new pathname. If the old name is removed, the file continues to exist with the new name. You cannot create a link to a directory.

Both oldfile and newname must specify USS HFS filenames. For programs not compiled with the posix option, style prefixes may be required. See File Naming Conventions for information on specifying USS filenames.

RETURN VALUE

link returns a 0 if it is successful; link increments the link count that refers to the number of links to the file. link returns a -1 if it is not successful; the link count is not incremented.

EXAMPLE

This example uses link and unlink to change the name of an HFS file. It differs from the rename function in two ways:

If the new name already exists, it fails and leaves the name unchanged.
It is not atomic, so errors could occur if another program simultaneously modifies the same directory entries.

#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>

int chname(char *oldname, char *newname) 
{
   int rc;
   rc = link(oldname, newname);
   if (rc != 0) {
      perror("link error");
      return -1;      /* Go no further if the link fails. */
   }
      /* The link worked. Now we can unlink the old name. */
   rc = unlink(oldname);
   if (rc != 0) {
      perror("unlink error");
      return -1;
   }
   return 0;
}

RELATED FUNCTIONS

symlink , unlink

SEE ALSO

Chapter 19, "Introduction to POSIX," in SAS/C Library Reference, Volume 2
File Management Functions

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