The Linux Phrasebook by Scott Granneman.

This is a handy book to have that can be read in at least two ways. Reading from page one straight through is a good way for users to become power users/junior system administrators.  The other way is to look up different topics as the need arises. Both ways can contribute to a much expanded knowledge of different commands.

Almost all the examples are well written, practical and illustrated via the command line interface.