Chapter 1. Introduction to Linux

Welcome to Running Linux, Version 5! When we wrote the first edition of this book, Linux had barely arrived on the scene. Our task seemed simple: help readers learn the basics of a new operating system that required a pretty fixed and predictable set of tasks. Few if any observers expected Linux would become a best-of-breed operating system, supported by the vast majority of hardware and software manufacturers on the planet. Who would have known that Linux would grow from a small user base of 30,000 people in 1995 to hundreds of millions only 10 years later? People use Linux everywhere on the planet and in some cases in outer space and under the ocean.

To the casual observer, Linux looks like a fairly simple personal computer desktop built on the same chassis as any IBM PC. People use Linux to browse the Internet, exchange email, listen to music, watch videos, and instant message their friends and coworkers. Students and office workers create documents with word processors, perform numerous tasks with spreadsheet programs, and make slide presentations.

The same Linux operating system also drives sonar arrays in nuclear submarines, indexes every document on the Internet, unifies large corporate data centers, runs nearly 70% of all web sites in the world, records your television programs, works in your cellular phone, and runs the switches that allow you to connect with your friends and family anywhere on the globe. Linux runs systems on the international space station as well as the shuttles that take astronauts there. It protects you from spam and computer viruses on numerous routers and back-end systems.

You can benefit directly from installing Linux on a system at home, at school, or in the office, and having all that power at your fingertips. Not only can you carry on everyday surfing and office work, but you can also learn how to write database queries, administer a web server, filter mail for spam and viruses, automate your environment through scripting languages, access web services, and participate in the myriad of other cutting-edge activities provided by modern computing.

How does Linux do all those things? Linux distributions harvest vast amounts of diverse technology, especially new and innovative developments in hardware. Developers have access to all the code that makes up the operating system. Although many people consider Linux the largest cooperative software development project in human history, Linux developers don't need to even know each other. If someone wants to write a software application, all he has to do is download the Linux code or visit its documentation site. If you started counting people who have contributed to the development of Linux and its associated projects, you would see hundreds of thousands of individuals.

Linux and open source software developers come from many walks of life. Major computer vendors such as IBM, HP, Novell, Red Hat, Sun, Dell, and others pay portions of their staffs to work on Linux. Universities around the globe sponsor projects and foundations that contribute to Linux. The U.S. Department of Defense, NASA, and the National Security Agency have paid for numerous pieces of the Linux operating system. Developing countries such as China, Brazil, Malaysia, South Africa, and Viet Nam, to mention a few, have added to the Linux base. Industrial giants such as Germany, Australia, Japan, the United Kingdom, and others have also made their presence felt. But in the very midst of those giants, many individuals such as you and me have also contributed to Linux.

During the 1990s, Linux generated more excitement in the computer field than any other development since the advent of microprocessor technology. Linux rejuvenated a dying technology sector following the fall of the dot-com boom in the spring of 2001. Today, Linux has surpassed the expectations of informed observers worldwide, including the authors of this book.

Early on, Linux inspired and captured the loyalty of its users. Technologists interested in the server side of the Internet needed to become familiar with the operating systems that ran web sites, domain name services, and email and service providers. Traditional software manufacturers priced their systems out of the range of those wanting to gain webmaster-type skills. Many people viewed Linux as a godsend because you could download it for free and gain the skills necessary to become a webmaster or system administrator while working on relatively low-cost hardware.

Originally, people saw Linux as simply an operating system kernel, offering the basic services of process scheduling, virtual memory, file management, and handling of hardware peripherals such as hard drives, DVDs, printers, terminals, and so forth. Other Internet operating systems belonged to the Unix family, which became available for commercial sale only after the breakup of AT&T and the Bell Operating Systems.

To skirt the legal issues surrounding AT&T's Unix, the Free Software Foundation (FSF) created a plethora of applications that performed many of the functions of basic Unix while using totally original FSF code instead of code produced by Bell Labs. This collection of FSF software was called GNU. To become a complete operating system, however, FSF needed a kernel. Although their own efforts in that area stalled, an operating system fitting the bill arose unexpectedly from efforts by a student at the University of Helsinki in Finland: Linus Torvalds.

People now use the term "Linux" to refer to the complete systemthe kernel along with the many applications that it runs: a complete development and work environment including compilers, editors, graphical interfaces, text processors, games, and more. FSF proponents ask that this broader collection of software be known as "GNU/Linux."