Perl 5 version 24.1 documentation
Deletes a list of files. On success, it returns the number of files it successfully deleted. On failure, it returns false and sets $! (errno):
On error, unlink will not tell you which files it could not remove. If you want to know which files you could not remove, try them one at a time:
Note: unlink will not attempt to 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. Finally, using unlink on directories is not supported on many operating systems. Use rmdir instead.