A GNU Debugger, originally created by Richard Stallman in 1986, is a standard debugger for the GNU operating system and an essential tool for software developers. Being a portable application, it is widely used on many Unix-like operating systems as well. In this article I’ll show some basic commands and techniques for debugging software with GDB. I’ll be using GDB version 7.9 under Arch Linux on x86-64, unless noted otherwise. Source code for this article is available on my GitHub site.