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)

Creating soft links and hard links

In the previous recipe, we touched on the subject of links. In this recipe, we'll learn more about links and how they affect inodes. We'll also investigate the difference between soft links and hard links. In short, a hard link is a filename, and a soft link is like a shortcut to a filename.

On top of that, we'll write two programs, one that creates a hard link and one that creates a soft link. We'll then use the program we created in the previous recipe to check the link count.

Getting ready

Except for the requirements listed at the beginning of this chapter, you'll also need the program we created in the previous recipe, my-stat-v1.c. You'll also need the test file we created in the previous recipe, named testfile1. If you haven't created those files yet, you can also download them from GitHub at https://github.com/PacktPublishing/Linux-System-Programming-Techniques/tree/master/ch5.

You'll also...