a script to recursively shorten all the file names in a directory

shorten.sh

#!/bin/bash
# this is a script to recursively shorten all the file names in a directory

function shorten() {
	cd "$1"
	pwd

	# rename all the files in the directory to numbers
	# if nessisary, move them to the temp directory to avoid name collisions
	i=1
	tempDir=""
	for file in * ; do
		# get the file extension if it exists, including the dot
		base="${file%%.*}"
		extension="${file#$base}"
		newName="$i$extension"
		# is there annother file in our way?
		if [ -e "$newName" ] ; then
			# create a temp directory if we don't already have one
			if [ -z "$tempDir" ] ; then
				tempDir="$(mktemp -d)"
			fi
			# move the file to the temp directory
			mv "$file" "$tempDir/$newName"
		else
			# just rename the file
			mv "$file" "$newName"
		fi
		((i++))
	done

	# if we had to relocate some files
	if [ -n "$tempDir" ] ; then
		# move them back to the original directory
		mv "$tempDir"/* .
		# remove the temp directory
		rmdir "$tempDir"
	fi
	
	# recursively call this function on all the subdirectories
	for file in * ; do
		if [ -d "$file" ] ; then
			shorten "$file"
		fi
	done
	
	cd ..
}

dir="$1"
if [ -z "$dir" ] ; then
	dir="."
fi
shorten "$dir"