How to batch rename files

This afternoon I needed to rename a bunch of files from one form to another in a command shell… Well technically I didn't need to do it in a shell - but, as sure as there is a hole in my ass, I wasn't gonna go through renaming them all manually!

They needed to go from, for example, add.png to add_32.png. After a little research into commands like printf, awk, bison and so on - I suddenly realized that 'cut' held the key!

for i in *; do j=`echo $i | cut -d . -f 1`; j=$j"_32.png"; mv $i $j; done


Basically, this says "for every file in the folder, cut the filename on all dots and take the first result into variable 'j'. Then append '_32.png' onto the end of the variable. Finally move the original file to the new filename".

I hope this saves someone else a bit of time!