SYSTEM CALLS
    unlink		- delete a link to a file

INVOCATION
    unlink( file_name )
      char *file_name;

EXPLANATION
    The file link <file_name> is deleted. If this was the last
    link to a file, and the file is not open, then the file will
    be removed.

RESULTS
     0 : Ok.
    -1 : Error.
