$ ls -l total 0 -rw-r--r-- 1 john john 0 Feb 1 20:23 four -rw-r--r-- 1 john john 0 Feb 1 20:23 one -rw-r--r-- 1 john john 0 Feb 1 20:23 two ? three $ ls | perl -nle 'BEGIN { $counter = 0 }; $old = $_; $new = "caption" . "$counter" . ".txt"; rename( $old, $new ); $counter++;' $ ls -l total 0 -rw-r--r-- 1 john john 0 Feb 1 20:23 caption0.txt -rw-r--r-- 1 john john 0 Feb 1 20:23 caption1.txt -rw-r--r-- 1 john john 0 Feb 1 20:23 two ? three