Crush / compress - jpg and png bash file

crush.sh

crush() {
	for f in *;
	do
		mv "$f" `echo $f | tr ' ' '_'`
	done

	for f in *.png
	do
		echo "$f"
		pngcrush -brute "$f"{,.} && du -b "$f"{,.}
		cp -f "$f." "$f"
	done

	for f in *.jpg
	do
		echo "$f"
		jpegtran "$f" > "$f." && du -b "$f"{,.}
		cp -f "$f." "$f"
	done
}

You need to install pngcrush and libjpeg-comps (for jpegtran) on your system.