Chapter 1. Introduction

Welcome to the Linux universe, one and all!

Linux has finally hit the mainstream; so much so that the first question I get from people these days is no longer, "What is Linux?" but rather, "What do I have to do to get Linux on my system?" For those who may want some clarification nevertheless, Linux is a fully multitasking operating system based on UNIX, although technically, Linux is the kernel, the master program that makes running a Linux system possible. That kernel, by the way, was written by a young Finnish student named Linus Torvalds. On August 25, 1991, Torvalds posted this now famous (perhaps legendary) message to the Usenet group comp.os.minix:

From: torvalds@klaava.Helsinki.FI (Linus Benedict Torvalds)
       Newsgroups: comp.os.minix
       Subject: What would you like to see most in minix?
       Summary: small poll for my new operating system
       Message-ID: <1991Aug25.205708.9541@klaava.Helsinki.FI>
       Date: 25 Aug 91 20:57:08 GMT
       Organization: University of Helsinki
       Hello everybody out there using minix -
       I'm doing a (free) operating system (just a hobby, won't be big and professional like gnu) for 386(486) AT clones. This has been brewing since april, and is starting to get ready. I'd like any feedback on things people like/dislike in minix, as my OS resembles it somewhat (same physical layout of the file-system (due to practical reasons) among other things).
       I've currently ported bash(1.08) and gcc(1.40), and things seem to work. This implies that I'll get something practical within a few months, and I'd like to know what features most people would want. Any suggestions are welcome, but I won't promise I'll implement them :-)
              Linus (
       PS. Yes - it's free of any minix code, and it has a multi-threaded fs. It is NOT protable (uses 386 task switching etc), and it probably never will support anything other than AT-hard disks, as that's all I have :-(.

Much has happened since then. Linus somehow captured the imagination of scores of talented programmers around the world. Joined together through the magic of the Internet, they collaborated, coded, tweaked, and gave birth to the operating system that is now revolutionizing the world of computing.

These days, Linux is a powerful, reliable (rock-solid, in fact), expandable, flexible, configurable, multiuser, multitasking, and completely free operating system that runs on many different platforms. These include Intel PCs, DEC Alphas, Macintosh systems, PowerPCs, and a growing number of embedded processors. You can find Linux in PDA organizers, digital watches, golf carts, and cell phones. In fact, Linux has a greater support base (in terms of platforms) than just about any other operating system in the world.

What we call the Linux operating system is not the work of just one man alone. Linus Torvalds is the original architect of Linux?its father, if you will?but his is not the only effort behind it. Perhaps Linus Torvalds's greatest genius lay in knowing when to share the load. For no other pay but satisfaction, he employed people around the world, delegated to them, worked with them, and asked for and accepted feedback in a next generation of the model that began with the GNU project.

GNU, by the way, is a recursive acronym that stands for "GNU's Not UNIX," a project of the Free Software Foundation. This project was started in 1984 with the intention of creating a free, UNIX-like operating system. Over the years, many GNU tools were written and widely used by many commercial UNIX vendors and, of course, system administrators trying to get a job done. The appearance of Linus Torvalds's Linux kernel has made the GNU dream of a completely free, UNIX-like operating system a reality at last.