bash (from the English. Bourne again shell, pun "Born again" shell - "revived" shell) - an improved and modernized variation of the command shell Bourne shell. One of the most popular modern versions of the UNIX command shell. Especially popular in the Linux environment, where it is often used as a pre-installed shell. Bash is a command processor that typically runs interactively in a text box. Bash can also read commands from a file called a script.