The administrators of Linux and Unix computers have been using text-based command-line interfaces called shell for many years to manage and administer their servers. As the Pi's OS, Raspbian, is a Linux variant, the most natural way to access and issue commands or check the status of running programs, services, and different servers on the Pi is again by issuing commands on this text-based shell. There are different shell implementations but the one that is used on Raspbian by default is bash. The most well-known way of accessing shell remotely on a Linux server is through the Secure Shell protocol known, in general, as SSH.