If you’re running your own Linux system, one of the first tasks at hand is to learn the ropes of system administration . You won’t be able to get by for long without having to perform some kind of system maintenance, software upgrade, or mere tweaking to keep things in running order.

Running a Linux system is not unlike riding and taking care of a motorcycle.^[*] Many motorcycle hobbyists prefer caring for their own equipment—routinely cleaning the points, replacing worn-out parts, and so forth. Linux gives you the opportunity to experience the same kind of “hands-on” maintenance with a complex operating system.

Although a passionate administrator can spend any amount of time tuning it for performance, you really have to perform administration only when a major change occurs: you install a new disk, a new user comes on the system, or a power failure causes the system to go down unexpectedly. We discuss all these situations over the next four chapters.

Linux is surprisingly accessible, in all respects—from the more mundane tasks of upgrading shared libraries to the more esoteric, such as mucking about with the kernel. Because all the source code is available and the body of Linux developers and users has traditionally been of the hackish breed, system maintenance is not only a part of daily life but also a great learning experience. Trust us: there’s nothing like telling your friends how you upgraded from PHP 4.3 to PHP 5.0 in less than half an hour, and all the while you were recompiling the kernel to support the ISO 9660 filesystem. (They may have no idea what you’re talking about, in which case you can give them a copy of this book.)

In the next few chapters, we explore your Linux system from the mechanic’s point of view—showing you what’s under the hood, as it were—and explain how to take care of it all, including software upgrades, managing users, filesystems, and other resources, performing backups, and handling emergencies.

Once you put the right entries in startup files, your Linux system will, for the most part, run itself. As long as you’re happy with the system configuration and the software that’s running on it, very little work will be necessary on your part. However, we’d like to encourage Linux users to experiment with their system and customize it to taste. Very little about Linux is carved in stone, and if something doesn’t work the way that you’d like it to, you should be able to change that. For instance, in earlier chapters we’ve shown you how to read blinking green text on a cyan background rather than the traditional white-on-black, if that’s the way you prefer it, or to add applets to your desktop panel. But this book also shows you something even more important: after installing a Linux distribution, you usually have lots of services running that you may not need (such as a web server). Any of these services could be a potential security hole, so you might want to fiddle with the startup files to get only the services you absolutely need.

It should be noted that many Linux systems include fancy tools to simplify many system administration tasks. These include YaST2 on SUSE systems, the Mandriva Control Center on Mandriva systems, and a number of utilities on Red Hat systems. These tools can do everything from managing user accounts to creating filesystems to doing your laundry. These utilities can make your life either easier or more difficult, depending on how you look at them. In these chapters, we present the “guts” of system administration, demonstrating the tools that should be available on any Linux system and indeed nearly all Unix systems. These are the core of the system administrator’s toolbox: the metaphorical hammer, screwdriver, and socket wrench that you can rely on to get the job done. If you’d rather use the 40-hp circular saw, feel free, but it’s always nice to know how to use the hand tools in case the power goes out. Good follow-up books, should you wish to investigate more topics in Unix system administration, include the Unix System Administration Handbook, by Evi Nemeth et al. (Prentice Hall) and Essential System Administration, by Æleen Frisch (O’Reilly).