Chapter 1. Introduction and Overview

Operating systems are not only regarded as a fascinating part of information technology, but are also the subject of controversial discussion among a wide public.^[] Linux has played a major role in this development. Whereas just 10 years ago a strict distinction was made between relatively simple academic systems available in source code and commercial variants with varying performance capabilities whose sources were a well-guarded secret, nowadays anybody can download the sources of Linux (or of any other free systems) from the Internet in order to study them.

^[] It is not the intention of this book to participate in ideological discussions such as whether Linux can be regarded as a full operating system, although it is, in fact, just a kernel that cannot function productively without relying on other components. When I speak of Linux as an operating system without explicitly mentioning the acronyms of similar projects (primarily the GNU project, which despite strong initial resistance regarding the kernel reacts extremely sensitively when Linux is used instead of GNU/Linux), this should not be taken to mean that I do not appreciate the importance of the work done by this project. Our reasons are simple and pragmatic. Where do we draw the line when citing those involved without generating such lengthy constructs as GNU/IBM/RedHat/HP/KDE/Linux? If this footnote makes little sense, refer to www.gnu.org/gnu/linux-and-gnu.html, where you will find a summary of the positions of the GNU project. After all ideological questions have been settled, I promise to refrain from using half-page footnotes in the rest of this book.

Linux is now installed on millions of systems and is used by home users and professionals alike for a wide range of tasks. From miniature embedded systems in wristwatches to massively parallel mainframes, there are countless ways of exploiting Linux productively. And this makes the sources so interesting. A sound, well-established concept (Unix) melded with powerful innovations and a strong penchant for dealing with problems that do not arise in academic teaching systems — this is what makes Linux so fascinating.