Deletes a list of files. Returns the number of files successfully deleted.
$cnt = unlink 'a', 'b', 'c';
unlink @goners;
unlink <*.bak>;
Note: unlink will not delete directories unless you are superuser and
the -U flag is supplied to Perl. Even if these conditions are
met, be warned that unlinking a directory can inflict damage on your
filesystem. Use rmdir instead.
If LIST is omitted, uses $_.