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)

Using errno with strerror()

Instead of looking up every possible errno macro and figuring out which ones apply and what they mean, it's easier to use a function called strerror(). This function converts the errno code into a readable message. Using strerror() is much faster than implementing everything ourselves. It's a lot safer, too, since there's less of a risk that we mess something up. Whenever there's a function available to ease the manual work for us, we should use it.

Do note that this function is meant to convert the errno macro into a readable error message. If we want to handle a particular error in some specific way, we still need to use the actual errno value.

Getting ready

The requirements from the previous recipe apply to this recipe. This means we need the GCC compiler, the Make tool (along with the Makefile), and the manual pages.

How to do it…

In this recipe, we'll continue developing our own version of touch. We&apos...