Creating GIF animation in Ubuntu

From the manual of 'covert'

The convert program is a member of the ImageMagick(1) suite of tools. Use it to convert between image formats as well as resize an image, blur, crop, despeckle, dither, draw on, flip, join, re-sample, and much more.

The above quoted paragraph is an understatement of the abilities of convert. Besides many amazing acts, Convert is capable of creating of animated GIF images. To do so, type the following in terminal:

$ convert -delay 100 -loop 0 image*.png animation.gif

For more on ImageMagick, I recommend this blog post.