All it takes is one line to resize a directory full of images to your desired size if you have the ImageMagick tools package installed. convert is a tool that comes with that package.

To install ImageMagick: (on Debian/Ubuntu based systems)

nits@excalibur:$ sudo apt-get install imagemagick

To only resize:

nits@excalibur:$ find . -iname '*.jpg' -exec convert {} -resize 120x120 {} \;

To resize and convert to another format (example converts JPEG to PNG):

nits@excalibur:$ find . -iname '*.jpg' -exec convert {} -resize 120x120 {}.png \;

Oh yeah! That’s all!

Here’s the YouTube video if you want to see it in action. Also, you get to see me make a fool of myself by making nervous typos :P