Linux Cookbook by Carla Schroder
I am not even sure where to begin with my praise of this book, it's got over a dozen sticky notes marking key sections that I find useful. I guess I can start by saying that the author is deeply involved with doing system administration via the command line, which is fantastic news for me! There are plenty of decent GUI tools out there, but when x dies and you're stuck at a command line, using them isn't an option. I feel that if you don't have the knowledge to fix things yourself, at least have a book by your side that offers you some tips, and that is what this book is for. And some people just prefer doing administration via the command line all the time, myself included.
The time I most often pull out this book, however, is not when I run into a problem, but when I'm setting up a new system. I don't reinstall often, but when I do there are little things that I often forget how to do, since I do them so infrequently. Things like setting up ssh keys, setting up users and groups, setting up NTP, setting up new fstab
I also found this book useful when I wanted a quick and clean explaination of different filesystems and more information about command line options for CD burning. Also I got some good ideas for backups and local file transfer methods from the chapter on Backup and Recover.
Best of all, this book contains a great chapter on kernels. So many books and online how-tos I've seen give you the steps of compiling a kernel, but don't explain what is going on. This always left me feeling like I had no clue what I was doing, and if there was an error I'd have no idea where I'd begin fixing it, since I didn't really know what "make mrproper," for instance, means (side note, she even quickly explains "according to Linux lore" the reasoning behind the name Mr. Proper, a delightful bit of trivia). Now that I've read this chapter on kernels I'm much more comfortable recompiling and customizing my own. She also talks about patching a kernel, which is something I had trouble with for a while, since so much documentation I found and people I asked said "just use patch" which meant nothing to me.
An excellent book for the linux user who wants to move away from the GUI and learn more about core, command-line administration.