gifsicle

TLDR

Optimize a GIF as a new file

$ gifsicle [path/to/input.gif] --optimize=3 -o [path/to/output.gif]

Unoptimize a GIF in place

$ gifsicle -b [path/to/input.gif] --unoptimize

Extract a frame from a GIF

$ gifsicle [path/to/input.gif] '#[0]' > [path/to/firstframe.gif]

Make a GIF animation from selected GIFs

$ gifsicle [*.gif] --delay=[10] --loop > [path/to/output.gif]

Reduce file size using lossy compression

$ gifsicle -b [path/to/input.gif] --optimize=3 --lossy=[100] --colors=[16] --dither

Delete the first 10 frames and all frames after frame 20 from a GIF

$ gifsicle -b [path/to/input.gif] --delete '#[0-9]' '#[20-]'

Modify all frames of a GIF using specific transformation options

$ gifsicle -b --crop [50],[50]+[-50]x[-50] --scale [0.25] --flip-horizontal --rotate-90 [path/to/input.gif]