Recursively optimize all PNG and JPG files from the location of the script.

optimize_images.sh

#!/bin/bash
find /uploads/sites/*/20* -type f -iname "*.png" -exec pngquant --speed 1 --skip-if-larger --strip {} \;
find /uploads/sites/*/20* -type f -iname "*.png" -exec advpng -z4 {} \;
find /uploads/sites/*/20* -type f -iregex .*\.jpe?g$ -exec jpegoptim -f -s -v -m 50 {} \;
touch optimg.flag
# find's -newer command option compares the timestamps of files found against a defined file, in our case optimg.flag
# when we finish optimizing all of the images we touch the optimg.flag file to update its timestamp