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)

Disabling echo for password prompts

To protect users' passwords from shoulder surfing, it's always best to hide what they type. The way to hide a password from being displayed is to disable echoing. In this recipe, we'll write a simple password program with echoing disabled.

Knowing how to disable echoing is key when writing programs that take some form of secret input, such as a password or a key.

Getting ready

For this recipe, you'll need the GCC compiler, the Make tool, and the generic Makefile.

How to do it…

In this recipe, we'll build a small program with a password prompt

  1. Since the code in this recipe will be rather long and some parts a bit arcane, I have split up the code into several steps. Note, however, that all code should go into a single file. Name the file passprompt.c. Let's start with the include lines, the main() function, and the variables we'll need. The struct named term of type termios is a special...