Introduction

In a nutshell, what you are reading is intended to be a shop class for computer science. Young computer science students are taught to "drive" the computer; but where do you go to learn what is under the hood? Trying to understand the operating system is unfortunately not as easy as just opening the bonnet. The current Linux kernel runs into the millions of lines of code, add to that the other critical parts of a modern operating system (the compiler, assembler and system libraries) and your code base becomes unimaginable. Further still, add a University level operating systems course (or four), some good reference manuals, two or three years of C experience and, just maybe, you might be able to figure out where to start looking to make sense of it all.

To keep with the car analogy, the prospective student is starting out trying to work on a Forumla One engine without ever knowing how a two stroke motor operates. During their shop class the student should pull apart, twist, turn and put back together that two stroke motor, and consequentially have a pretty good framework for understanding just how the Formula One engine works. Nobody will expect them to be a Formula One engineer, but they are well on their way!

Not everyone wants to attend shop class. Most people only want to drive the car, not know how to build one from scratch. Obviously any general computing curriculum has to take this into account else it won't be relevant to its students. So computer science is taught from the "top down"; applications, high level programming, software design and development theory, possibly data structures. Students will probably be exposed to binary, hopefully binary logic, possibly even some low level concepts such as registers, opcodes and the like at a superficial level.

This book aims to move in completely the opposite direction, working from operating systems fundamentals through to how those applications are complied and executed.

This book is only possible thanks to the development of Open Source technologies. Before Linux it was like taking a shop course with a car that had it's bonnet welded shut; today we are in a position to open that bonnet, poke around with the insides and, better still, take that engine and use it to do whatever we want.