Optimized image optimization script (pngcrush & jpegtran)

optimize.sh

#!/bin/sh

# script for optimizing images in a directory (recursive)
# pngcrush & jpegtran settings from:
# http://developer.yahoo.com/performance/rules.html#opt_images

# pngcrush
for file in `find -E . -regex '.*\.(jpg|png)'`; do
    if [ ${file: -4} == ".png" ]
    then
        echo "crushing $file ..."
        pngcrush -rem alla -reduce -brute "$file" temp.png

        # preserve original on error
        if [ $? = 0 ]; then
            mv -f temp.png $file
        else
            rm temp.png
        fi
    else
        echo "crushing $file ..."
        jpegtran -copy none -optimize -progressive "$file" > temp.jpg

        # preserve original on error
        if [ $? = 0 ]; then
            mv -f temp.jpg $file
        else
            rm temp.jpg
        fi
    fi
done