Running Linux, Fourth Edition

Preface

"Technical knowledge is not enough. One must transcend techniques so that the art becomes an artless art, growing out of the unconscious."

—Daisetsu Suzuki (1870-1966)

This is a book about Linux, a free, open source operating system that’s changing the world of computing. In this book, we show how you can completely change the way you work with computers by exploring a powerful and free operating system. Linux goes against the traditional computing mainstream, being developed by a loosely organized group of thousands of volunteers across the Internet. Linux started as a real underground movement — guerrilla hacking, if you will — and brings a lot of excitement, discovery, and self-empowerment back into today’s corporate-dominated computing culture. We invite you to dive in, enjoy yourself, and join the throng of people who know what it means to tweak your dot clocks and rdev your kernel image.

The Zen quote at the beginning of this preface summarizes our philosophy in this book. We’re targeting readers who are inquisitive and creative enough to delve full-tilt into the world of Linux, and who want to get at the heart of the system. Linux represents a rebellion against commercial operating systems, and many of its users like living on the edge of the latest technological trends. Of course, the casual reader can set up and run a Linux system (or hundreds of them!) without much trouble, but the purpose of this book is to dig more deeply into the system — to bring you completely into the Linux mentality, to reach Linux “enlightenment.” Rather than gloss over messy details, we explain the concepts by which the system actually works so that you can troubleshoot problems on your own. By sharing the accumulated expertise of several Linux experts, we hope to give you enough confidence to call yourself a true Linux Guru. (Your first koan: what is the sound of one user hacking?)

You have in your hands the fourth edition of Running Linux, and by most accounts this book is considered the classic text on installing, maintaining, and learning to use a Linux system. The first edition was published way back in 1996, and had its roots in a free book called Linux Installation and Getting Started, which is still floating around the Internet. Since then, Running Linux has gone through many improvements and changes to keep the text up-to-date with the latest developments in the Linux world. Kalle Dalheimer joined Matt Welsh and Lar Kaufman for the third edition, and has done most of the updates for this edition as well. Terry Dawson has contributed some material on security.

In this edition, we have completely updated the installation, configuration, and tutorial information to be up-to-date with the latest Linux software distributions (including Red Hat and its derivatives, SuSE, and Debian) and many application packages. The core of the book, however, has not changed much. This was intentional: in the first three editions we made a great effort to make the book as robust as possible, even though Linux itself is under constant development. No book can adequately capture everything there is to know about Linux. (You won’t find chapters here on using Linux on the Space Shuttle, or on finding weaknesses in data encryption algorithms, although it’s been done!) Our approach has worked remarkably well and has been preserved in this new, updated edition. We think this book will be of use to you for a long time to come.

The world of Linux has changed a lot since the last edition of Running Linux. Apart from increased performance and robustness, Linux sports an increasing range of applications, from personal productivity tools to high-end databases. Linux is used to running mission-critical services, and drives many popular Internet sites, search engines, and content delivery networks. Linux is also being increasingly adopted on the desktop, and desktop systems such as KDE and GNOME are making it easier than ever before to get the most out of Linux.

In the preface to the first edition, we said that “Linux has the potential to completely change the face of the PC operating system world.” Looking back, it’s clear that our prediction was right! Linux has erupted into the computing mainstream with an amazing force: it has been covered by every major media channel, has helped usher in the so-called “Open Source Revolution,” and is widely claimed as the most viable competitor to Microsoft’s dominance in the operating systems market. Today, most estimates place the number of Linux users worldwide at well over 200 million. Linux has matured to the point where many people can dive in and start using Linux without knowing most of the hairy details behind device drivers, XFree86 configuration files, and bootloaders. Still, we think it’s best to give you some of the behind-the-scenes views, so you have an understanding of the workings of the system, even if it’s not strictly necessary for casual Linux use.

Why People Like Linux

There are many reasons why people are finding that Linux is the right operating system for them. It might have to do with cost, performance, flexibility, size, or features. Or it might have something to do with that intangible thrill that you get from running your own system, rather than simply installing a bunch of software that comes out of a box. Windows XP and Mac OS X are good operating systems, but they are focused on the needs of home users. As such, they have some limitations and are a lot less flexible than Linux. Here are a few reasons why people are switching to Linux:

• It’s free. That is, Linux is a freely redistributable clone of the Unix operating system. You can get Linux free from someone who has it or from the World Wide Web, or you can buy it at a reasonable cost on CD-ROM from a vendor who has packaged it (probably with added value), possibly with support services. Linux is also “free as in speech” (not just “free as in beer”): anyone can modify and distribute modifications and improvements to the system. (We’ll get into all of this later, when we talk about open source and free software.)

• It’s popular. It runs on a wide range of hardware platforms, including popular Pentium (Pentium II, III, and 4), AMD, and Cyrix chips, and even older 386/486 machines. Linux also runs on higher-end systems based on the Itanium, SPARC, or Alpha architectures, as well as on PowerPC and 68k-based Macs. Linux even runs on IBM 390 mainframes, and stripped-down versions run on personal digital assistants (PDAs) like the Palm Pilot and Compaq iPAQ. Linux supports a broad range of hardware, including video cards, sound cards, CD-ROMs, disk drives, printers, scanners, and many other devices.

  Linux has an enormous user community presence on the World Wide Web, with many web sites devoted to providing information and discussion about the system. A growing number of commercial software vendors are developing applications for Linux, including Corel WordPerfect Office 2000 Suite, the StarOffice suite from Sun Microsystems, and a number of database products from big names such as Oracle, Informix, and IBM.

• It’s powerful. Linux is efficient and fast, and makes excellent use of hardware. Many users switching to Linux from Windows are surprised at how fast and responsive the system is, even with many processes running and with multiple windows open. A Linux machine with a reasonably fast processor and a sufficient amount of memory can perform as well, or better, than Unix workstations costing tens of thousands of dollars. Linux is a multiuser, multitasking operating system that can run many applications (and even have many users logged into the same system) at once. Linux also supports multiprocessor systems, and Linux is commonly used in high-end server environments where this kind of hardware is the norm. Linux is used for building large “clusters” consisting of hundreds of machines connected with a fast network, used for massive scientific calculations or for driving large web sites.

• It’s under your control. Whereas most GUI-heavy proprietary systems embody a policy of keeping the user as ignorant of system processes as possible, Linux is very open and makes it easy for you to know what is happening under the hood. At the same time, if you like, you can relinquish some control and rely on easy-to-use tools like SuSE’s yast.

• It’s robust. Linux is being developed in the open by thousands of programmers, as well as numerous companies and universities, all contributing new features, performance enhancements, and bug fixes. It incorporates the work of these many developers in the form of advanced compilers, editors, and utilities. As a result, Linux is extremely robust; many users have Linux systems that stay up for months at a time (say goodbye to the “blue screen of death!”). Linux has an enormous base of freely available applications, ranging from desktop publishing and office suites to scientific tools to multimedia applications to games.

• It’s full-featured. Linux supports of the features of modern Unix-based operating systems, including virtual memory, threads, multiprocessors, and advanced networking (including IPv6, DHCP, firewalling, network address translation, and more). Linux supports a vast array of software packages, programming languages, and hardware devices. Linux uses the X Window System graphical user interface (GUI) and supports several advanced desktop environments, including KDE and GNOME (all covered later in this book).

• It’s highly compatible with Windows. Linux will happily coexist on the same machine as any flavor of Windows (including Windows 95/98/NT, Windows 2000, or Windows XP), or other operating systems such as OS X and FreeBSD. Linux can directly access Windows files, either across the network, or on the Windows portions of your hard drive on the same system. Using the popular Samba tool, Linux can also act as a Windows file and print server. Note that Linux does not run under Windows; it is completely independent of it, but features have been added to allow the separate systems to work together.

• It’s small. The core operating system can run on just 8 MB of system memory, including a desktop GUI and several applications. A basic Linux system can fit into 20 MB or so of disk storage, and many people run a basic Linux “rescue system” from a single 1.44 MB floppy! Linux has even been tuned to run on low-memory embedded systems (such as those used in network routers or robots), and in hand-held PDAs.

• It’s big. Some of the larger distributions can fill several gigabytes of disk space with applications, source code, and datafiles. The number of powerful utilities and applications ported to Linux grows constantly. Most Linux users can run a complete system in 300 MB or so of disk space. This includes all the basics, as well as nice extras such as programming libraries, compilers, text-processing tools, and more. But if you’re a real power user, much more is available.

• It’s supported. The most important line of support is the many web sites devoted to Linux, as well as the many newsgroups and mailing lists online. You can also contract for support from an independent company or buy a supported version of Linux from one of its distributors.

• It’s well-documented. There is this book (a good start, we commend you on that!), which is also available in Spanish, German, French, Italian, Portuguese, Czech, Polish, Chinese, Taiwanese, and Japanese. The Linux development community established the Linux Documentation Project (LDP) early on, which maintains a large amount of online documentation about the system. The many books, FAQ lists, and “how-to” documents from the LDP can guide you through almost any task that needs to be done under Linux. Once you get over a few installation humps, Linux is more or less like any other Unix system, so the many general books about Unix use and administration will give you all the help you need. Finally, there is the popular press, which has written hundreds of books on Linux — both introductory and advanced — which have been translated into most major languages around the world.

• It’s sexy. Let’s face it: there’s nothing particularly daring or edgy about running the latest shrink-wrapped release from the world’s largest software company (need we name names?). Linux has an attitude, a philosophy, and a joie de vivre that you’re not going to find in any other operating system. There’s much, much more to Linux than a bunch of bits on a CD-ROM . . . can you dig it?