This book is mainly devoted to programming in the GNU/Linux environment. The authors take a teaching approach, consistently presenting the most important concepts and techniques for using the advanced capabilities of the GNU/Linux system in application programs. Readers will learn to write programs with an interface that Linux users are accustomed to; master technologies such as multitasking, multi-threaded programming, inter-task communication and interaction with hardware devices; will be able to improve their programs, making them faster, more reliable and safer; will understand the features of the GNU/Linux system, its limitations, additional features and specific conventions. The book is intended for programmers who are already familiar with the C language and have basic experience in GNU/Linux.