The gem command is the command line user interface to the RubyGems system for managing Ruby packages.

This command has a few sub-commands itself and a long list of options that differ per sub-command. Remembering and typing them can be tedious, but thankfully, if you are using the bash command shell, it can help with this task. It only has to be told how.

I’ve packaged the how in this file. Copy it to /etc/bash_completion.d and hope that your bash installation picks it up the next time you start a shell.

On Debian/Linux system that’s just how it works. If this does not work on your particular version of Linux or Unix, you’ll have to look up how completions are handled on your system.