shell

A process that handles the user interaction with the operating system. From the shell, the user can execute operating system commands. A shell is usually provided to contain activity in a particular part of the computer system. In DOS, for example, the shell handles command line input, and standard output and error reporting. DOS shells have their own special commands that are not usable within applications. They even have their own special variables and scripting facilities that make the user interface customizable.

See also command line, environment variable, operating system, process.