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 system calls – and when not to use them

System calls are an exciting topic in any conversation about Unix and Linux. They are one of the lowest parts when it comes to system programming in Linux. If we were to look at this from a top-down approach, the shell and the binaries we run would be at the top. Just below that, we have the standard C library functions, such as printf(), fgets(), putc(), and so on. Below them, at the lowest levels, we have the system calls, such as creat(), write(), and so on:

Figure 3.1 – High-level functions and low-level functions

When I talk about system calls here in this book, I mean system calls as C functions provided by the kernel, not the actual system call table. The system call functions we use here reside in user space, but the functions themselves execute in kernel space.

Many of the standard C library functions, such as putc(), use one or more system call functions behind the curtains. The putc...