Shell (operating system)

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In computer science , a shell is the software that a user uses to interact with an operating system - a  human-machine interface . During kernel the core referred to an operating system, the shell (is English for "Cup", "sheath" or "outer skin") clear the outer layer and thus interface ( English interface ) to the user.


Shells usually work either

depending on the type and purpose of the operating system.

Shells working in rows

Terminal emulation (image section)
Terminal emulation (image section)

A line by line text processing Shell - here called text Shell - provides the user with a working environment for the input and output with a so-called command line ( English commandline ) prepared in which he commands ( English commands inputs) supported by the text shell interpreted to be. Text shells are mainly used by experienced users, as commands must be known. These are primarily so-called Unix shells ( Bash , TENEX-C shell , Z shell, etc.) as an elementary component of Unix and similar systems. Windows has a simple command prompt and the newer and more feature-rich PowerShell , but Bash can now also be used. Such text shells usually provide their own scripting language .

Graphic shells

Mouse pointer "pointer" and "hand"

A graphical shell provides an environment with a graphical interface for use, which is referred to as a user interface . Operating and control elements with symbols or text labels can be found "on" this two-dimensional surface , which preferably suggest a three-dimensional depth using visual effects - for example, windows appear to be on top of each other or a button appears raised, and when triggered it is apparently pressed in. An operating system is more easily accessible, since functions , routines or subroutines can be called up with a mouse click or a tap on an element. Desktop environments in personal computers as well as the environments of smartphones and modern televisions, for example, form graphic shells. A terminal emulation that provides a text shell (e.g. Bash, PowerShell, etc.) can often be used.


  • Jörg R. Mühlbacher: Operating Systems. Basics. Univ.-Verl. Trauner, Linz 2009. ISBN 3-85499-591-1

See also