I want to add leading zeros to my file names using Bash (Shell) so they get renamed from rock0.py .. rock500.py to rock000.py ... rock500.py. Please tell me why the following code is not working:

rename 's/rock(\d+)/rocksprintf("%03d", $1)/e' rock*.py

I get the following error message:

-bash: syntax error near unexpected token `('

Please let me know if there is a better code that will work. Thank you