For more experienced users, there are plenty of cool tools and shortcuts to make the book worthwhile (sdiff, head, and procmail, for example). The authors provide a generous section on scripting--a good introduction for advanced users who may be spending too much time on repetitive tasks. The authors also touch on how to intelligently include regular expressions in searching, a pleasant addition to an already outstanding section.
Some of the authors' decisions on what to include merit warning, although not enough that users should turn away from this book: the authors only cover the bash, ksh, and csh shells; they focus on only the pico and vi editors--not emacs; and their excellent section on e-mail covers only pine (briefly mentioning that elm really isn't worth its salt for a new user). While the book isn't all-inclusive, it isn't meant to be. The authors make their preferences clear, and for the user, this amounts to a good deal of clarity and time saved. --Jennifer Buckendorff