Author is a recognized Linux expert--PC Magazine calls Peterson ""an impressive technical writer."" Contains alphabetical reference of every major Linux command, syntax, description, and example. Provides time-saving insight as to when a certian command is better used over another. Efficiently covers the various Linux programmilng shells--BASH (standard, easy-to-use commands, TCSH (syntax similar to C, more of a traditional structure), and the Z shell (incorporates features of other two shells with better support for functions).