Ruby is a very powerful programming language and thanks to its many features, it can be used for many different purposes. From this module on, we will focus on how to use Ruby for penetration testing purposes. One of the first topics we will cover is ‘Regular Expression.’ Regex is widely used in the security field; it is used to find and locate important information stored in files, web pages, network communication and so on. A good knowledge of how to use and define regex is a ‘must’ for a penetration tester! During the study of this module, the student will also learn how to use date and time classes as well as manage and interact with files and directories: read, delete, create and so on.