Mastering UNIX Shell Scripting 2e: Bash, Bourne, and Korn Shell Scripting for Programmers, System Administrators, and UNIX Gurus by Michael (16-May-2008) Paperback
One of the better programming 'How To' texts I've ever used. At the time my focus was on Korn shell, this book does a good job of translating the various shells with similar examples and I like examples. There is also an online stash of example scripts you can download.
I still use it as a reference and reminder to what i wrote back when, mmm what did I mean by that line?
You will need to start somewhere. This “Mastering UNIX Shell Scripting by Randy Michael” gives a fair introduction to the subject.
Some scripters will find this too comprehensive and need to supplement it with other reading. Others will find this too fundamental but occasionally there is a good idea that was not thought of.
Some people just need a guide to help them get off the ground fast. No matter what category you are in this is an excellent reference for your library.