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)

Checking if it's a TTY

In this recipe, we'll start looking at some of the C functions to examine TTYs. Here, we mean TTY in the broadest sense, meaning both TTY and PTY.

The program we will write here will check if stdout is a terminal. If it's not, it will print an error message.

Knowing how to check if stdin, stdout, or stderr are terminal devices will enable you to write error checks for programs that require a terminal to work.

Getting ready

For this recipe, we'll need the GCC compiler, the Make tool, and the generic Makefile. The generic Makefile can be downloaded from this chapter's GitHub folder, at https://github.com/PacktPublishing/Linux-System-Programming-Techniques/tree/master/ch9.

How to do it…

Here, we'll write a small program that prints an error message if stdout is not a terminal:

  1. Write the following small program in a file and save it as ttyinfo.c. We use two new functions here. The first one is isatty...