Linux Server Hacks is filled with tips and techniques (written in cook-book style) for getting various things done in Linux. I don't know that I'd go so far as to call them hacks, but there are a few useful tips contained in the book. As computer books go, this one is pretty long in the tooth (published in 2003) and there are a few things that are probably no longer current unless you're using a 5 year old Linux distro. For the most part though, a lot of the tips and tricks in the book should be pretty portable to any system and usable even on newer versions.
There are 100 tips in 8 sections covering a wide range of topics from Server Basics to Backups, Revision Control, SSH and Networking to name a few. Personally, I found the sections on SSH, Networking and Information Services to be the most interesting and useful.
Some of the tips in the book are a little on the esoteric side and probably not useful for everybody. If you're already familiar with Linux internals and diving into the command line, you might find a few useful tidbits in this book to use.
3.5 stars out of 5.