It's really easy to create an animated GIF from a bunch of frames on the command line using ImageMagick.
By Matthew Malinowski, 2012-12-04
I had a happy discovery today when looking for ways to get iTerm2 to not render bold fonts so poorly.
Awesome! An easy way to make animated GIFs from PNG.
For many more amazing things, ImageMagick-related and otherwise, check out this list of handy shell commands on Lauri's site.