My first book, published in 2001. As of 2013, it is still being used as a teaching guide in several college and university computer science courses.
From the jacket:
"Respected Linux Journal and Sys Admin columnist Marcel Gagne has written the definitive guide to Linux system administration: a book that will be invaluable for sys admins at all levels of experience, using any leading distribution. Linux System Administration offers hands-on, results-focused coverage of every key Linux configuration and management task. Gagne offers detailed coverage of installation, Linux file management tools and file naming conventions; disks and file systems; users and groups; hardware; X-based graphical desktops; networking; kernel building; printing; and much more. The book contains practical guidance on scripting and automating administration tasks; administration tools; Internet services; security; tuning; and more. Gagne goes far beyond the basics, offering expert guidance on becoming a smarter sys admin — from avoiding problems to tracking trouble calls and identifying resources that can provide the solutions you need. The book concludes with a series of instant-reference "cheat sheets" designed to help sys admins get the most common jobs done fast. For everyone responsible for administering Linux systems, including both experienced and new sys admins, as well as those migrating from UNIX or Windows environments. Also for power users, and any user or administrator who must maximize the security of their Internet-connected workstations."
You can pick up a copy from Amazon.com, Amazon.ca, Kindle, Kobo, or Chapers-Indigo. And probably lots of other places.