1. <operating system> (Originally from Multics
, widely propagated via Unix
) The command interpreter
used to pass commands to an operating system
; so called because it is the part of the operating system that interfaces with the outside world.
The commonest Unix shells are the c shell (csh
) and the Bourne shell (sh
2. (Or "wrapper") Any interface program that mediates access to a special resource or server
for convenience, efficiency, or security reasons; for this meaning, the usage is usually "a shell around" whatever.