Batch rename all files in a folder to lower case on a Mac

You need to know how to use Mac OS terminal app:

  1. Open Terminal.app, type cd and then drag and drop the Folder containing the files to rename into the Terminal window.
  2. If needed, confirm you’re in the correct directory, type ls and hit enter. You will see a list of all files in the directory.
  3. Paste this code and hit enter:
    for f in *; do mv "$f" "$f.tmp"; mv "$f.tmp" "`echo $f | tr "[:upper:]" "[:lower:]"`"; done

If needed, confirm that all your files are renamed to lowercased, type ls and hit enter again.