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)

Starting a new process with system()

What we just covered regarding using fork(), waitpid(), and execl() to start a new program in a forked process is the key to understanding Linux and processes at a deeper level. This understanding is key to becoming an excellent system developer. However, there is a shortcut. Instead of manually dealing with forking, waiting, and executing, we can use system(). The system() function does all these steps for us.

Getting ready

For this recipe, you only need what's listed in the Technical requirements section of this chapter.

How to do it…

In this recipe, we'll rewrite the previous program—my-fork—using the system() function instead. You'll notice how much shorter this program is compared to the previous one. Let's get started:

  1. Write the following code in a file and save it as sysdemo.c. Notice how much smaller (and easier) this program is. The system() function does all the complex stuff...