A variety of different shells are available for Linux and Unix, each with pros and cons. While bash (updated version of sh) and tcsh (descended from C-shell/csh) are the most common shells, the choice of shell is entirely up to user preference and availability on the system. In most Linux distributions, bash is the default shell.

The purpose of a shell is to interpret commands for the Operating System (OS) to execute. Since bash and other shells are scripting languages, a shell can also be used for programming via scripts. The shell is an interactive and customizable environment for the user.

All examples in this tutorial use the bash shell.