Question

A non-elegant, non-flexible way of doing this would be something like this:

for path in *.jpg # IMG_1067_CR2.jpg, MG_1068_CR2.jpg, etc.
do
    mv "$path" "${index-0}.jpg"
    let index+=1
done
unset index

A much better way should support leading zeros (for example for ffmpeg), avoid tainting the environment with dummy variables, have a dry-run option (like rename), and should not require specifying the extension twice. Is this supported by existing tools?

Alternatively, how can I make this solution work with leading zeros:

rename -n 's/IMG_([0-9]*)\.jpg/$1/; $_="IMG_".($_-1067).".jpg"' *.jpg 

Answer 1

You can do:

rename -n 's/IMG_([0-9]*)\.jpg/$1/; $_="IMG_".substr("000" . ($_-1067), -4).".jpg"' *.jpg

which will render “0” as “0000” and “907” as “0907”.