Ask HN: How to introduce a non-programmer to the command line, file system, etc.

I’m a CS major, and my wife is an English major. A little while ago, my wife expressed interest in learning more about how computers work. Not the physics and the silicon or low-level kernel stuff; more userland-level, practical knowledge. What are some resources to help a non-programmer casually interested in learning more become familiar with the command line, file system, UNIX philosophy, etc.?