Batch optimise images with a single command

gistfile1.txt

#For jpeg files
#Need to install jpegtran in ubuntu
sudo apt-get install libjpeg-progs

Usage tips:
#To optimise a single jpeg image:
    jpegtran -copy none -optimise -outfile image.jpg image.jpg
    
#To optimise all jpegs in the current directory:
    for img in `ls *.jpg`; do jpegtran -copy none -optimise -outfile $img $img; done
    
#To optimise all jpegs in the current directory and all child directories:
    find . -name “*.jpg” -print0 | xargs -0 -I filename jpegtran -copy none -optimise -outfile filename filename

#For png files
#optipng is a great little command line tool in Linux that can be used to optimize images for web.
#Need to install optipng in ubuntu
sudo apt-get install optipng

Usage tips:
$ optipng infile.png -out outfile.png

$ optipng -k file1.png file2.tiff file3.gif
* -k option ensures that a backup of the original files are retained. Else, the original files will be over written – if they are PNG of course.

$ optipng -o5 file1.png file2.tiff file3.gif
* -o option indicates the levels of optimization. -o5 indicates 5 levels of optimization.