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)

Reading inode information and learning the filesystem

Understanding inodes is the key to understanding the filesystem in Linux at a deeper level. A filename isn't the actual file in a Linux or Unix system. It's just a pointer to an inode. The inode has information about where the actual data is stored and a lot of meta data about the file, such as the file mode, last modification date, and owner.

In this recipe, we'll get a general understanding of the filesystem and how inodes fit into this. We will also view inode information and learn a few commands for that. We will also write a small C program that reads inode information from a filename.

Getting ready

In this recipe, we'll use both commands and C programs to explore the concepts of inodes. Everything you need for this recipe is covered in the Technical requirements section of this chapter.

How to do it…

In this recipe, we'll begin by exploring the commands that already exist on the...