Book Image

Linux System Programming Techniques

By : Jack-Benny Persson
5 (1)
Book Image

Linux System Programming Techniques

5 (1)
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)

Making the new daemon a systemd service

Now that we've made a new-style daemon in the previous recipe, we'll see that it's even easier to make a unit file for this daemon.

Knowing how to write unit files to new-style daemons is important since more and more daemons are written this way. When making new daemons for Linux, we should make them in this new style.

Getting ready

For this recipe, you'll need to complete the previous one. It's the daemon from that recipe that we'll use here.

How to do it...

Here, we will make the new-style daemon a systemd service:

  1. Let's begin by moving the daemon to /usr/local/sbin, just as we did with the traditional daemon. Remember, you'll need to be root for this:
    $> sudo mv new-style-daemon /usr/local/sbin/
  2. Now we'll write the new unit file. Create the /etc/systemd/system/new-style-daemon.service file and give it the following content. Remember, you'll need to be root to create...