In Unix, a popular command interpreter with a built-in programming language.
The Bourne shell, developed by Dr. Steven Bourne of Bell Labs, is the oldest Unix shell still in popular use and features a built-in command set for writing shell scripts, background execution of commands, input and output redirection, job control, and a set of shell variables to allow environment customization.
See also Bash; C shell; Korn shell; Linux; Unix shell.