I'm guessing you probably won't find many books on Mac shell details exactly. However, you will find a lot more books on Linux and and Shell programming since it's a more popular platform right now.
Put together a Linux box, get a book on Linux shell programming and start learning. The bash shell used in Linux is essentially the same bash shell used on the Mac.
Some of the details and system level commands are a little different, but the concepts of how to program in bash, how to use pipes, and how to move around a Unix filesystem is going to be pretty much the same on Macs and Linux boxes.
I can't personally recommend a book because I learned how to use the Unix shell environment many years ago in college. There it was on Sun, NeXT, and early Linux boxes.