> extensive descriptions of all system utilities (87 of them, by the appendix count)
> detailed descriptions of administration procedures (accounts / groups and their creation / deletion / modification, system backup, etc, etc)
> extensive glossary, appendices
> covers all major shells (bash, tcsh, zsh)
> thorough listings / examples

Basically, this volume is the only Linux reference you will ever need. Newer or proprietary packages are not necessarily covered, but everything in the standard distribution is here.