It was designed to help remind *nix system administrators of options for commands that they use frequently, but not frequently enough to remember.

Let’s imagine a completely hypothetical world where it’s the umpteenth time you’ve used it, but you still can’t remember which flags to send to tar… so you run:

cheat tar

You’ll be greeted by:

# To extract an uncompressed archive:
tar -xvf '/path/to/foo.tar'

# To extract a .gz archive:
tar -xzvf '/path/to/foo.tgz'

# To create a .gz archive:
tar -czvf '/path/to/foo.tgz' '/path/to/foo/'

# To extract a .bz2 archive:
tar -xjvf '/path/to/foo.tgz'

# To create a .bz2 archive:
tar -cjvf '/path/to/foo.tgz' '/path/to/foo/'

The cheatsheets themselves are community-sourced.