This is a comment on the first edition that I have used for a couple of years but, looking at the TOC of the Second Edition, it seems to still apply.

The list of commands in Chapeter 2 is in alphabetical order only. If you remember the name of a command you can use man pages instead of the book but if you don't, the book does not help.

A few pages at the beginning, listing the commands by task and cross referencing to other commands would make the book much more useful.