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)

Handling more errno macros

We'll continue to handle more errno macros in our version of touch in this recipe. In the previous recipe, we managed to provoke an Unknown error message since we only handled permission denied errors. Here, we'll find out what exactly caused that error and what it is called. We'll then implement another if statement to handle it. Knowing how to find the correct errno macros will help you gain a deeper understanding of computing, Linux, system calls, and error handling.

Getting ready

Once again, we'll examine the manual pages to find the information we are looking for. The only things that are needed for this recipe are the manual pages, the GCC compiler, and the Make tool.

How to do it…

Follow these steps to complete this recipe:

  1. Start by reading the manual page for creat() by using man 2 creat. Scroll down to the ERRORS heading. Read through the descriptions of the different macros. Eventually, you'll...