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)

Compiling with Make

We have already seen some example usage with Make. Here, we will recap on what Make is and how we can use it to compile programs so that we don't have to type GCC commands.

Getting ready

All you need for this recipe is the GCC compiler and Make. You have already installed these tools if you followed Chapter 1, Getting the Necessary Tools and Writing Our First Linux Programs.

How to do it…

We will write a small program that calculates the circumference of a circle, given the radius. We will then use the Make tool to compile it. The Make tool is smart enough to figure out the name of the source code file.

  1. Write the following code and save it as circumference.c. This program is built on the same code as mph-to-kph.c from the previous chapter:
    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    #define PI 3.14159
    int main(void)
    {
       char radius[20] = { 0 };
       while(fgets(radius, sizeof...