Reddit mentions of From Bash to Z Shell: Conquering the Command Line

Books that I find very useful:

Beginning Portable Shell Scripting: From Novice to Professional

From Bash to Z Shell: Conquering the Command Line

Unix Power Tools, Third Edition

The UNIX Programming Environment

Running Linux (mine is old, but still useful)

I have bought lots of other useful books from O'Reilly.

Anything written by Michael W Lucas.

I have been a Unix admin for 5+ years and I am always finding cool tricks with commands I have been using for years. Or built in shell commands even, such as:

http://www.amazon.com/Bash-Shell-Conquering-Command-Line/dp/1590593766/ref=sr_1_1?ie=UTF8&qid=1319107875&sr=8-1

Is one of the books I have been going back over.

Interactive or scripted?

Interactive

Online tutorials can answer any questions you might ever have, but when learning something new I like the condensed nature of a well written book on a subject. For shells, I thought this book was excellent, and still reference it from time to time:
http://www.amazon.com/Bash-Shell-Conquering-Command-Line/dp/1590593766/ref=sr_1_1?ie=UTF8&qid=1290060461&sr=8-1

also.... ZSH FOR LIFE!

From Bash to Z Shell: Conquering the Command Line

Learning shell by looking at a few examples didn't work well for me. That book explained a lot of things that I hadn't understood.

Note that this may be overkill...