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)

Error handling and errno

Most of the system call functions in Linux and other UNIX-like systems set a special variable called errno when an error occurs. This way, we get a general error code from the return value (often -1) and then more specific information about what went wrong by looking at the errno variable.

In this recipe, we'll learn what errno is, how to read values from it, and when it is set. We'll also see an example use case of errno. Learning about errno is imperative to system programming, primarily since it's used in conjunction with system calls.

The next few recipes in this chapter are closely tied to this recipe. In this recipe, we'll learn about errno; in the following three recipes, we'll learn how to interpret the error codes we get from errno and print human-readable error messages.

Getting ready

You'll need the same components for this recipe that we used in the previous one; that is, the GCC compiler, the Make tool...