I cut my Linux teeth on Gentoo stage 1 and 2 installs, which I found enormously frustrating and equally educational.

Today, I'd recommend working through Linux From Scratch. You'll develop a rich understanding of how a UNIX-like OS fits together, including a fair bit of shell functionality: http://www.linuxfromscratch.org/lfs/

My favourite dead-tree UNIX book would be UNIX Power Tools, 3rd Edition (http://www.amazon.com/Power-Tools-Third-Shelley-Powers/dp/05...). It may be a while before it's a truly valuable resource, but keep it in mind.