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:

for file in rock*.py; do mv "$file" "rock$(printf "%03d" ${file#rock}).py" done

Please let me know if I am making a spacing error or anything as I am super new to Bash, so I have no idea why my file names are not changing to add leading zeros at the start. If you have a different code that might work, feel free to share! Thank you