05_754935 ch01.qxp 11/7/05 9:38 PM Page 9 Chapter 1 What Is SUSE Linux? In This Chapter ᮣ Explaining what Linux is ᮣ Going over what SUSE Linux includes ᮣ Introducing you to what SUSE Linux helps you do ᮣ Getting started with SUSE Linux bet you’ve heard about Linux, even if you may not know much about SUSE I(pronounced soo-za) Linux. Even if you haven’t, don’t worry: I’ll explain everything about Linux, what the different names like SUSE and Red Hat mean, what SUSE Linux includes, and how to get started with SUSE Linux. By the way, SUSE Linux runs on computers with Intel 80x86 and Pentium processors (basically any PC that can run any flavor of Windows). If you have a PC, you can install SUSE Linux on it and experience firsthand what the fuss is all about. Getting a Handle on Linux You know that your PC is a bunch of hardware — things you can touch, like the system box, monitor, keyboard, and mouse, as shown in Figure 1-1. The system box contains the most important hardware of all — the central pro- cessing unitCOPYRIGHTED(CPU), the microchip that runs MATERIAL the software (any program that tells the computer how to do your bidding), which you actually can’t touch. In a typical Pentium 4 PC, the Pentium 4 microprocessor is the CPU. Other important hardware in the system box includes the memory (RAM chips) and the hard drive — and one program has to run all this stuff and get it to play nice: the operating system. 05_754935 ch01.qxp 11/7/05 9:38 PM Page 10 10 Part I: Getting to Know SUSE Memory Transient storage where programs are loaded and executed by the CPU Output Central Processing Unit (CPU) Figure 1-1: The computer's brain—the microprocessor—that executes the instructions contained in the program A simplified Input view of a loaded into memory computer and how User it runs Disk computer Permanent storage where programs are loaded programs. and data are stored in files The operating system is software that manages all the hardware and runs other software at your command. You, the user, communicate those commands by clicking menus and icons or by typing some cryptic text. Linux is an operating system — as are UNIX, Windows 98, Windows 2000, and Windows XP. The Linux operating system — also called the Linux kernel — is modeled after UNIX. The operating system is what gives a computer — any computer — its person- ality. For example, you can run Windows 98 or Windows XP on a PC — and on that same PC, you can also install and run Linux. That means, depending on which operating system is installed and running at any particular time, the same PC can be a Windows 98, Windows XP, or Linux system. The primary job of an operating system is to load software (computer pro- grams) from the hard drive (or other permanent storage) into the memory and get the CPU to run those programs. Everything you do with your com- puter is possible because of the operating system — so if the operating system somehow messes up, the whole system freezes up. You know how infuriating it is when your favorite operating system — maybe even the one that came with your PC — suddenly calls it quits just as you were about to click the Send button after composing that long e-mail to your friend. You try the three-finger salute (pressing Ctrl+Alt+Del), but nothing happens. Then it’s time to try the Reset button (provided your computer’s builders were wise enough to include one). Luckily, that sort of thing almost never happens with Linux — it has a reputation for being a very reliable operating system. In technical mumbo jumbo, Linux is a multiuser, multitasking operating system. This means that Linux enables multiple users to log in, and Linux can run more than one program at the same time. Nearly all operating systems are 05_754935 ch01.qxp 11/7/05 9:38 PM Page 11 Chapter 1: What Is SUSE Linux? 11 Does Linux really run on any computer? Well, it runs on almost any computer. Let’s family; Alpha AXPs; Sun SPARCs and see. Nowadays, you can get versions of UltraSPARCs; Hewlett-Packard’s HP PA-RISC; Linux for systems based on Intel 80x86, Pentium, the PowerPC and PowerPC64 processors; the and other Intel compatible processors; AMD’s MIPS R4x00 and R5x00; even IBM mainframes. 64-bit AMD64 processors; the Motorola 68000 multiuser and multitasking these days, but when Linux first started in 1994, multiuser and multitasking were big selling points. All the different names that you hear for Linux — SUSE, Red Hat, Debian, Fedora, Knoppix, MEPIS, Ubuntu, Xandros, you name it — are actually the names of different Linux distributions. A Linux distribution is basically the Linux kernel (the operating system) together with a huge collection of applications, along with an easy-to-use installation program. By the way, most people just say Linux to refer to a spe- cific Linux distribution. Many different Linux distributions exist, and each includes the standard Linux operating system and the following major packages: ߜ The X Window System: The graphical user interface. ߜ One or more graphical desktops: Among the most popular are GNOME and KDE. ߜ A collection of applications: Linux programs come in the form of ready- to-run software, but the source code (the commands humans use to tell the computer what to do) is included (or easily available), as is its documentation. Current Linux distributions include a huge selection of software — so much that it usually requires multiple CD-ROMs or a single DVD-ROM (which this book includes). The development and maintenance of the Linux kernel, software packages in a Linux distribution, and the Linux distributions themselves are organized as open source projects. In a nutshell, open source means you have access to the source code and the right to freely redistribute the software without any restrictions. My succinct definition is pretty basic, so to find out more details of what open source means and to see some acceptable open source licenses, please visit the Open Source Initiative Web site at www.opensource.org. 05_754935 ch01.qxp 11/7/05 9:38 PM Page 12 12 Part I: Getting to Know SUSE Discovering SUSE Linux SUSE Linux is a commercial distribution that focuses on the desktop and includes some proprietary components that prevent its redistribution. You can buy SUSE Linux online or in computer stores and bookstores. If you have heard about open source and the GNU (GNU’s not UNIX) license, you may think that no one can sell Linux for a profit. Luckily for companies that sell Linux distributions, the GNU (pronounced gah-nu) license — also called the GNU General Public License (GPL) — does allow commercial, for-profit distri- bution, but requires that the software be distributed in source-code form, and stipulates that anyone may copy and distribute the software in source-code form to anyone else. Several Linux distributions are available free of charge under the GPL. In August 2005, Novell sponsored and established the openSUSE project — a worldwide community program for promoting the use of Linux everywhere. Specifically, at www.openSUSE.org developers, end users, and other open source enthusiasts can collaborate to evolve a freely available SUSE Linux Open Source Software (OSS). Novell’s commercial SUSE Linux retail product is based on SUSE Linux OSS. The retail SUSE Linux is similar to SUSE Linux OSS except that the commercial version includes some packages that are not open source or cannot be distributed freely. This book includes SUSE Linux 10.0 OSS from the openSUSE project. I tell you a lot more about SUSE in this book, but you can also visit www.suse. com for more information (especially the latest news) about SUSE Linux. Making sense of Linux version numbers Both the Linux kernel and a Linux distribution such as SUSE Linux have their own version numbers, not to mention the many other software programs (such as GNOME and KDE) that come with the Linux distribution. The ver- sion numbers for the Linux kernel and the Linux distribution are unrelated, but each has particular significance. Linux kernel version numbers After Linux kernel version 1.0 was released on March 14, 1994, the loose-knit Linux development community adopted a version-numbering scheme. Version numbers such as 1.X.Y and 2.X.Y, where X is an even number, are considered the stable versions. The last number, Y, is the patch level, which is incremented as problems are fixed. For example, 2.6.13 is a typical, stable version of the Linux kernel. Notice that these version numbers are in the form of three inte- gers separated by periods — Major.Minor.Patch — where Major and Minor are numbers denoting the major and minor version numbers, and Patch is another number representing the patch level. 05_754935 ch01.qxp 11/7/05 9:38 PM Page 13 Chapter 1: What Is SUSE Linux? 13 Version numbers of the form 2.X.Y with an odd X number are beta releases for developers only; they may be unstable, so you should not adopt such ver- sions for day-to-day use. For example, when you look at version 2.7.5 of the Linux kernel, the 7 in the minor version number tells you it’s a beta release. Developers add new features to these odd-numbered versions of Linux. You can find out about the latest version of the Linux kernel online at www.kernel.org.