gifcomb(1) on Linux
The text 54fb3f5d5e81, as Debian 8 (Jessie), Debian 7 (Wheezy), Debian 6.0 (Squeeze) shipped it. The page shows this text now.
A program to combine 2 GIF images of exactly the same size into one. The color maps are merged, but the result may not exceed 256 colors. A boolean mask GIF file can be used to set which pixel from two images to use at each location. Otherwise any background color from first image is converted to second image color at that point. Only the first image of each file is combined; again, all files' first images must be of exactly the same size.