Hoo boy. I thought I'd seen everything, but I was wrong. There's a free book available - or you can buy it if you want some extra goodies - named Unix for the Beginning Mage that teaches you the command line shell using the metaphor of wizards & magic & other D&D-like stuff. It's perfect for the Half-Elf Paladin in your life!
(Check out all of my posts on the shell.)
