Linux System Programming, 2nd Edition

Chapter 1. Introduction and Essential Concepts

This book is about system programming, which is the practice of writing system software. System software lives at a low level, interfacing directly with the kernel and core system libraries. Your shell and your text editor, your compiler and your debugger, your core utilities and system daemons are all system software. But so are the network server, the web server, and the database. These components are entirely system software, primarily if not exclusively interfacing with the kernel and the C library. Other software (such as high-level GUI applications) lives at a higher level, delving into the low level only on occasion. Some programmers spend all day every day writing system software; others spend only part of their time on this task. There is no programmer, however, who does not benefit from an understanding of system programming. Whether it is the programmer’s raison d'être, or merely a foundation for higher-level concepts, system programming is at the heart of all software that we write.

In particular, this book is about system programming on Linux. Linux is a modern Unix-like system, written from scratch by Linus Torvalds and a loose-knit community of programmers around the globe. Although Linux shares the goals and philosophy of Unix, Linux is not Unix. Instead, Linux follows its own course, diverging where desired and converging only where practical. The core of Linux system programming is the same as on any other Unix system. ...