LINUX: Rute Users Tutorial and Exposition is the only Linux sysadmin's guide proven by 50,000+ Web users. It presents in-depth coverage of all aspects of system administration: user management, security, networking, Internet services, packages, config files, shell scripting, and more. It also contains detailed cross-references to LPI and RHCE certification topics, making it invaluable for exam preparation.
The key difference between Microsoft Windows and UNIX is that Windows is meant to be easy to learn, while UNIX is meant to compensate for a steep learning curve by providing extraordinary flexibility to knowledgeable users. Linux: Rute User's Tutorial and Exposition is the best book on the market in terms of flattening that learning curve. The author, Paul Sheer, uses this book as the text for a class he teaches, and its instructional value is unquestionable. Rather than attempt to make analogies for the way things are done in Windows or in Mac OS, or try to satisfy readers' requirements with mere recipes, Sheer tries to inculcate his readers into the Linux way of thinking. The idea is that work gets done differently in Linux, and you have to get a few concepts clear in order to work effectively in the environment.
Take, for example, Sheer's discussion of the /etc/passwd file, which is at the core of user authentication. He provides a listing of a typical /etc/passwd file, then explains what each element on each line is for. This leads smoothly into a discussion of /etc/shadow, the shadow password file, and its capacity for hiding passwords behind a one-way hash algorithm. Sheer's prose is unfailingly clear and detailed, which is good because he's chosen to omit graphics altogether (which means, incidentally, that this book focuses on the command shell--bash, to be precise--and even the chapter on X Windows lacks screen shots). Aside from a few weird typographical choices (a tiny picture of a penguin invariably follows the word "Linux" in body text, for example), this is a faultless book.--David Wall
Topics covered: How to be a competent Linux user, familiar with the command line, key utilities like "sed," and important related skills like C programming, shell scripting, and regular expression creation. There's coverage of server software--notably HTTPd, Sendmail, and Exim--and coverage of the PostgreSQL server.