Book Image

Linux System Programming Techniques

By : Jack-Benny Persson
Book Image

Linux System Programming Techniques

By: Jack-Benny Persson

Overview of this book

Linux is the world's most popular open source operating system (OS). Linux System Programming Techniques will enable you to extend the Linux OS with your own system programs and communicate with other programs on the system. The book begins by exploring the Linux filesystem, its basic commands, built-in manual pages, the GNU compiler collection (GCC), and Linux system calls. You'll then discover how to handle errors in your programs and will learn to catch errors and print relevant information about them. The book takes you through multiple recipes on how to read and write files on the system, using both streams and file descriptors. As you advance, you'll delve into forking, creating zombie processes, and daemons, along with recipes on how to handle daemons using systemd. After this, you'll find out how to create shared libraries and start exploring different types of interprocess communication (IPC). In the later chapters, recipes on how to write programs using POSIX threads and how to debug your programs using the GNU debugger (GDB) and Valgrind will also be covered. By the end of this Linux book, you will be able to develop your own system programs for Linux, including daemons, tools, clients, and filters.
Table of Contents (14 chapters)

Forking a process

Previously, we have been saying spawned when a program creates a new process. The correct terminology is to fork a process. What's happening is that a process creates a copy of itself—it forks.

In the previous recipe, we learned how to execute a new program inside a process using execl(). In this recipe, we'll learn how to fork a process using fork(). The forked process—the child—is a duplicate of the calling process—the parent.

Knowing how to fork a process enables us to create new processes on the system programmatically. Without being able to fork, we are limited to only a single process. For example, if we want to launch a new program from an existing one and still keep the original, we must fork.

Getting ready

Just as in the previous recipes, you'll need the pstree tool. The Technical requirements section covers how to install it. You'll also need the GCC compiler and the Make tool. You'll also...