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)

FIFO – using it in the shell

In the previous recipe, I mentioned that there's a disadvantage to the pipe() system call—it can only be used between related processes. But there's another type of pipe we can use, called a named pipe. Another name for it is First In, First Out (FIFO). Named pipes can be used between any processes, related or not.

A named pipe, or a FIFO, is actually a special kind of file. The mkfifo() function creates that file on the filesystem, just like any other file. Then, we use that file to read and write data between processes.

There's also a command named mkfifo, which we can use directly from the shell to create named pipes. We can use this to pipe data between unrelated commands.

In this introduction to named pipes, we'll cover the mkfifo command. In the next two recipes, we'll write a C program using the mkfifo() function and then another program to read the pipe's data.

Knowing how to use named pipes...