Linux/UNIX
Providing a summary of Linux in a few paragraphs is a difficult task. Unlike other operating systems, each of which has only a single variation, Linux is a freely distributable open source operating system that has many variants called distributions. Each of these distributions offers a slightly different approach to certain aspects of the operating system, such as installation and management utilities. Some of the most common Linux distributions include Red Hat, SuSE, Debian, and Caldera. In light of the many versions of Linux, if a command or an approach is listed in this section and is not available in the version of Linux you are using, you can look for an equivalent command or approach in your version, and you will very likely find one.