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)

Message queues – creating the receiver

In the previous recipe, we built a program that created a message queue named /my_queue, and then sent three messages to it. In this recipe, we'll create a program that receives the messages from that queue.

Getting ready

Before you start this recipe, you need to have completed the previous recipe. Otherwise, there will be no messages for us to receive.

You'll also need the GCC compiler and the Make tool for this recipe.

How to do it…

In this recipe, we'll receive the messages we sent in the previous recipe:

  1. Write the following code in a file and save it as msg-receiver.c. This code is a bit longer than the code for the sending program, so it's been broken up into several steps, each one explaining a bit of the code. Remember, though, that all the code goes into the same file. We'll start with the header files, the variables, the struct, and a character pointer named buffer. We&apos...