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 files and updating the timestamp

Now that we understand the filesystem, inodes, and hard links, we'll learn how to create files by writing our own version of touch in C. We have already started writing a version of touch in Chapter 4, Handling Errors in Your Programs, where we learned about error handling. We will continue using the latest version of that program, which we named simple-touch-v7.c. The real version of touch updates the modification and access timestamp of a file if the file exists. In this recipe, we'll add that feature to our new version.

Getting ready

Everything you'll need for this recipe is listed in the Technical requirements section for this chapter. Although we will add on the latest version of simple-touch, we'll write the entire code in this recipe. But for complete comprehension of the program, it is wise to read through Chapter 4, Handling Errors in Your Programs, first.

How to do it…

In this eighth version...