optimize images with mozjpeg recursively

mozjpeg.sh

#!/bin/bash
#
# usage: bash mozjpeg.sh directory
#
find "$1" -type f -name '*.jpg' -print0 | while read -d $'\0' file
do
    echo ${file}
    mkdir -p opt/"$(dirname "$file")"
    djpeg $file | cjpeg -quality 80 | jpegtran -optimize -progressive > opt/$file
done