renum.sh version 0.03
http://ix.io/15kv

Try this version out instead. Test it out on a small patch of files (copy some into a directory). I changed it to copy the files into a new directory called renum, then you can delete the original files yourself. If you like how it works you can modify it from cp -n to mv -n , and it should be OK. I'm removing the bad post. My apologies for the error.