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)

Learning about what orphans are

Understanding what orphans are in a Linux system is just as crucial as understanding zombies. This will give you a deeper understanding of the entire system and how processes get inherited by systemd.

An orphan is a child whose parent has died. However, as we have learned in this chapter, every process needs a parent process. So, even orphans need a parent process. To solve this dilemma, every orphan gets inherited by systemd, which is the first process on the system—PID 1.

In this recipe, we'll write a small program that forks, thus creating a child process. The parent process will then exit, leaving the child as an orphan.

Getting ready

Everything you need for this recipe is listed in the Technical requirements section of this chapter.

How to do it…

In this recipe, we will write a short program that creates an orphan process that will be inherited by systemd. Let's get started:

  1. Write the following code...