As the copy on the back of this book claims, the O'Reilly 'Bash Pocket Reference' allows one to "quickly find answers to the annoying questions that always come up when you're writing shell scripts." As you would expect, this is a reference manual, and unless you already know the fundamentals of BASH, it won't be of much use, unless used in conjunction with another, more expansive book. My favorite part of this book so far has been its treatment of more obscure shell variables, and its quick reference for shell builtins.
I should point out, though (and this is something that a previous reviewer seems to have missed), that this guide does *not* cover the use/syntax of all the external programs one might find on a *NIX system (e.g., grep, find, etc.). The reference is to BASH only and its associated builtin commands. And to be honest, external commands don't really *need* a reference like this, since they should already have man-pages that explain their usage.
Considering the price and the abundance of information, the BASH pocket reference is a great buy for anyone who does even casual work in the BASH shell.
Linux users know all to well that typing "man bash" or "info bash" in the text console is like opening The Bible and starting at Genesis when you want to read a chapter from St. Luke. Of course, the way the Bash man pages are written, Jesus may come back by the time you finish reading it.
For those who would like to write shell scripts and learn from the Bash man pages but don't have an eternity to spare reading a verbose document on such an easy programming tool, the Bash Pocket Reference is for you.
Because my eyes (and pocketbook) have yet to adjust to the concept of eBooks, the dead tree edition is preferred. Combine working knowledge with other books (like the sed & awk Pocket Reference and the Linux Pocket Guide) and internet resources with this book and you'll be writing shell scripts like a pro in just a few hours. Then after a few days, you'll start to kick butt writing shell scripts that do things that GUI based programs do but at a price of memory consumption. (BTW, use a text editor like vim or emacs when programming! Learning how to use screen or tmux also couldn't hurt, in fact it will make things more productive provided you can memorize various combinations to complete tasks.)
I highly recommend this book for anyone using Linux or UNIX as their operating system.
This is a good and concise reference for the syntax and semantics of the Bash shell. But note that the book does NOT cover any actual Linux commands such as "cp" or "find"! The Bash Pocket Reference is for advanced users, its focus is on shell scripting. You can look up how to declare variables and functions, redirect output, how Bash evaluates arithmetic expressions etc. If you're looking for a Linux command reference for beginners, try Linux Shell Commands: A Tutorial Quick Reference for Desktop Users.
I do network security, and have a lot of reference guides, the Bash pocket reference guide is pretty good, it is well organized, and easy to understand. Just remember though, this is not something to buy if you are new to bash, this is a reference guide.
One can never go wrong with an O'Reilly publication. Had this on a previous job and found it extremely helpful as an everyday tool. Delivered as advertised in excellent conditon. Seller to be both commended and recommended.