Introduction

Welcome to Red Hat Linux!

If you're new to Linux, choosing a Linux distribution to install can be confusing. Relax! You've made the right choice in choosing Red Hat Linux. Nearly 60% of Linux installations either are Red Hat or based on Red Hat Linux. You also made the right choice in choosing Red Hat Linux 7 Unleashed! This is the latest edition of the best-selling book on Red Hat Linux. A whole new team of authors has been put together for this edition with the task of giving you all the details about installing, administering, and using the latest version of the newest and best alternative computer operating system for today's PCs. You'll find CD-ROMs in the back of this book that contain the latest version of Intel-based Red Hat Linux and all the software you'll need to get started.

If you're a fan of Linux, you know that Linux is growing in popularity by leaps and bounds. Even better, major improvements and updates to existing software have been made right along with the increase in the Linux user base—Linux is now even easier to install! You'll also be quite pleased to learn about the new features and improvements included with the latest Linux kernels, such as support for a number of USB devices. If you've read a previous edition of Red Hat Linux Unleashed, take note of the vast number of improvements we've made to this edition. I think you'll agree that Red Hat Linux 7 Unleashed is an indispensable companion for the advanced Linux user.

What Is Linux?

Linux is the core of the operating system, or the kernel, while the Linux operating system and its collection of software is properly known as a distribution. Many of the programs in a Linux distribution come from the Berkeley Software Distribution, or BSD UNIX, and the Free Software Foundation's GNU software suite. Linux melds SysV UNIX and BSD features with POSIX compliance, and has inherited much of the best from more than 25 years of UNIX experience. Linux has also helped provide the recent impetus for the Open Source Software movement.

First released on October 5, 1991, by its author and trademark holder, Linus Torvalds, then at the University of Helsinki (now at Transmeta in California), Linux has spawned an increasingly vocal legion of advocates, users, and contributors from around the world. Originally written as a hobby, Linux now supports nearly all the features of a modern multitasking, multiuser operating system.

Linux is a full-fledged operating system. It provides full multitasking in a multiuser environment. Linux offers high-quality software at a cost far lower than other commercial versions of UNIX, and Red Hat Linux takes Linux a step further.

Red Hat, Inc. is a computer software development company that sells products and services related to Linux. Since 1993, Red Hat has built a solid reputation and marketable trademark by providing one of the very best implementations of Linux. After an initial public offering in August 1999, Red Hat, Inc. has grown and expanded, with ventures into numerous new Open Software-related technologies and markets. Red Hat's mission is to provide professional tools to computing professionals. Red Hat provides these tools by doing the following:

• Building tools, which Red Hat releases as freely redistributable software available for unrestricted download off of thousands of sites on the Internet

• Publishing books and software applications

• Manufacturing shrink-wrapped software, versions of the Linux OS, making Linux accessible to the broadest possible range of computer users

• Offering professional training and certification

• Providing technical support

Red Hat has a customer-oriented business focus, and recognizes that the primary benefits of the Linux OS are the availability of complete source code and its "freely distributable" GNU General Public License (also known as the GPL; see the GNU GENERAL PUBLIC LICENSE in the back of this book). This gives any home, corporate, academic, or government user the ability to modify the technology to his or her needs and to contribute to the ongoing development of the technology to the benefit of all users.

Using Linux provides benefits such as security and reliability that commercially restricted, binary-only operating systems simply cannot match. Some of these benefits include

• There are no royalty or licensing fees. Linus Torvalds holds the Linux trademark, but the Linux kernel and nearly all of the accompanying software is distributed under the GNU GPL. This means that you get source code to nearly everything.

• Linux runs on nearly any CPU. Linux runs on more CPUs and different platforms than any other computer operating system. One of the reasons for this, beside the programming talents of its rabid followers, is that Linux comes with source code to the kernel and is quite portable. There are versions for the Compaq Alpha, Sun SPARC, and even Motorola's low-power DragonBall processor (used in the Palm Pilot and other embedded systems). Linux for Intel-based computers from the 386 on up is on this book's CD-ROMs.

• Linux extends the life of legacy hardware. Recent trends in the software and hardware industry are to push consumers to purchase faster computers with ever-increasing amounts of system memory and hard drive storage. Linux doesn't suffer the prevalent bloat of "creeping featurism," and works quite well, even on aging x486-based computers with limited amounts of RAM. This means you'll get more life out of your older computers.

• Linux controls the software and you control Linux. This means that, on the rare occasion a program crashes, Linux won't collapse like a house of cards. You can kill the program and continue working with confidence. Linux uses sophisticated, state-of-the-art memory management to control all system processes. You won't lose control, and won't have to suffer the indignities of rebooting the system.

• Linux works very well as a personal computer UNIX for the desktop. You'll find many popular applications available for Linux, such as Netscape Navigator and Corel's WordPerfect. Red Hat Linux includes 3,000 or more programs (such as word processors, and spreadsheet and graphics applications), and a graphical interface, the X Window system. The included Red Hat Linux 7.0 is one of the newest Linux distributions, and uses an up-to-date version of the latest stable Linux kernel with several features of the new 2.4-series of the Linux kernel, such as support for a number of Universal Serial Bus devices. You'll also find the very latest in X11 window managers and software libraries. Tasks such as installing, configuring, and managing Linux are becoming point-and-click operations.

• Linux works well for server operations. If you need a support platform for server operations, Linux has real advantages, especially when compared to the cost of other operating systems, such as Windows 2000. Linux just makes sense for many home budgets and business financial models. Why anyone would pay $3,500 or more for a 25-client license to use proprietary server software when you can get the same functionality and even more for the price of this book is beyond me.

Linux, like UNIX, is a very modular operating system. The skills required to select, compile, link, and install the various components that are needed for a complete Linux OS can be beyond the experience of most people who might want to use Linux. The various Linux distributions go a long way toward solving this for the average Linux user, but most don't address the problem of how to upgrade your Linux system once you get it successfully installed. Most users found it easier to delete their whole Linux system and reinstall from scratch when they needed to upgrade.

What makes Red Hat Linux different is that its distribution is easier to install and maintain. There are a number of good reasons why nearly 60% of Linux users choose Red Hat Linux and Red Hat–based Linux distributions. These reasons include advanced package management, graphical (point and click!) system installation and control, and custom system administration tools. Red Hat Linux also includes an advanced version of the linuxconf utility, which makes system administration a snap!

Probably the best feature of Linux, the GNU utilities in general, and Red Hat Linux in particular, is that they are distributed under the terms of the GNU Public License (GPL). This feature has allowed research institutions, universities, commercial enterprises, and hackers to develop and use Red Hat Linux and related technologies cooperatively without fear that their work would someday be controlled and restricted by a commercial vendor. Use of the GPL (and similar licensing) is a growing trend among enlightened programmers, and an important ingredient in preventing the spread of restrictive patents and proprietary software.

The huge development effort and wide distribution of the Linux OS will ensure its place as a real, viable, and significant alternative to commercially restricted operating systems. The open development model, availability of source, and lack of license restrictions are features that commercial operating system developers simply cannot offer. Software development groups that need this model include groups from government-affiliated research organizations, to academic research and teaching projects, to commercial software application developers.

The number of new applications becoming available for Linux and the rapidly growing user base of these technologies are causing even the largest computer industry organizations to take Linux seriously. And Red Hat, Inc. is a serious contender, with corporate customers such as Boeing, Burlington Coat Factory, Iomega Corporation, Cisco Systems, Deutsche Bank, GTE, Oracle, GTSI, Hewlett-Packard, Hughes, IKEA, Intel, New York Life, Nationwide Insurance, Southwestern Bell, and Suzuki. Red Hat, Inc. is also involved with academic institutions such as Carnegie Mellon University, CERN Laboratories, the University of North Carolina, and the University of Rochester. Red Hat Linux is even used by government entities such as NASA, the U.S. Postal Service, and the Internal Revenue Service!

Even Datapro (a McGraw-Hill Company), in its recent 1996 survey of the UNIX industry, concluded that programmers are taking a hard look at the viability of Linux on production platforms now that Linux costs less than Microsoft and has the added benefits of UNIX, such as great performance, inherent power tool sets, and communication capabilities. Two years later, International Data Corporation estimated that Linux's market share grew 212% in 1998, with the number of Linux shipments nearly tripling, from 236,000 to 748,000. Note that this does not take into account the number of users downloading Linux for free from the Internet. This explosive interest is even more evident today, as IBM, Compaq, Hewlett-Packard, and Sun Microsystems announced in August 2000 the creation of the GNOME Foundation to build consensus and software for the Linux desktop. The Silicon Valley Linux Users Group estimates there are now 32 million Linux users worldwide, with the number set to double every six months!

Recent studies now show that more than half of the Web servers used around the world are run on Open Source software such as Apache. This shows the quality, power, and success of open software in taking on the commercial operating systems and succeeding.

With the purchase of this book, you are taking the first step necessary to take back control of your computing system from a closed-source, monopolistic software industry. You'll find the experience of stepping off the commercial software treadmill exhilarating and rewarding. There is an exciting future for Red Hat Linux, and we are glad that you are now a part of it!

Who Is This Book's Intended Audience?

This book is aimed at the intermediate to advanced computer user. You should be familiar with Linux or another version of the UNIX operating system. However, if you're a new user, this book will help you install Red Hat Linux and configure the X Window System for your Intel-based computer.

What This Book Can Offer You

The Red Hat Linux distribution goes a long way toward solving administrative and management tasks for the average Linux user. This book aims to provide technical advice on advanced topics, such as setting up Domain Name Service, configuring Apache, and understanding how to control system services. You'll also find advice throughout the book regarding system security, a topic of ever-increasing importance as more and more computer systems join the Internet.

How This Book Is Organized

The book is divided into the following five parts:

• Part I: "Red Hat Linux—Installation and User Services" —You'll read detailed instructions and technical tips on getting Red Hat Linux installed and configured for your computer. You'll learn how to configure and get the most out of the X Window System, how to choose the best X window manager or graphical interface for Red Hat Linux, how to connect to the Internet, and how to choose various graphic and multimedia tools.

• Part II: "Configuring Services"—This part contains nine chapters aimed at helping you set up local and network services for your system—essential information required for Internet operations.

• Part III: "System Administration and Management"—All Red Hat Linux systems require administration and management. Whether you have 1 user or 1,000 users, these chapters contain critical advice and analysis of software tools and administrative procedures used every day with Linux, including backup and restoration and security.

• Part IV: "Red Hat Development and Productivity"—Red Hat Linux comes with a wealth of programming and productivity tools. This section gives an overview of programming for Linux in C, how to use shell scripting, automate computer tasks, rebuild the Linux kernel, and use emulators and other windowing clients.

• Part V: "Appendixes"—You'll learn more about the licensing used for Red Hat Linux and read about the most often used software tools; you'll also get a handy cross-reference listing of the software included with this book's CD-ROMs.

Conventions Used in This Book

The following typographic conventions are used in this book:

• Code lines, commands, statements, variables, and any text you type or see onscreen appear in a computer typeface. When lines of input and output are shown, bold computer typeface is often used to show the user's input.

• Placeholders in syntax description appear in an italic computer typeface. Replace the placeholder with the actual filename, parameter, or whatever element it represents.

• Italics highlight technical terms when they first appear in the text and are being defined.

• A special icon is used before a line of code that is really a continuation of the preceding line. Sometimes a line of code is too long to fit as a single line in the book, given the book's limited width. If you see before a line of code, remember that you should interpret that "line" as part of the line immediately before it.