Fh: File history with ed, diff, awk, sed, and sh

fh uses a chain of ed(1) scripts to construct any version of a file. I saw the following passage in diff(1) of 7th Edition UNIX:

The -e option produces a script of a, c and d commands for the editor ed, which will recreate file2 from file1. Only an ancestral file ($1) and a chain of version-to-version ed scripts ($2,$3,…) made by diff need be on hand.

Source: github.com