If you're going to copy code from another node (Re^2: Find duplicate files.) then at least use the download link, and not just copy/paste with the mouse.

Then you won't have all those plus signs in there that show you have not even compiled ("perl -c file...") the downloaded code.

If you want to start with that code, then all you'd have to do is to changed the rename statement so that it calls a non-damaging function instead. Then tweak to your heart's delight. Give It A Try.