Shell

Shell

A shell is a user interface for access to an operating system's services. In general, operating system shells use either a command-line interface (CLI) or graphical user interface (GUI), depending on a computer's role and particular operation. It is named a shell because it is an outer layer of interface between the user and the innards of the operating system (the kernel).

Types of Shells

Command-Line Interface (CLI)

A command-line interface (CLI) is a text-based user interface used to view and manage computer files. Examples of CLI shells include the Bourne shell (sh), the C shell (csh), the Korn shell (ksh), and the Bourne Again shell (bash).

Graphical User Interface (GUI)

A graphical user interface (GUI) shell provides a graphical means of interacting with the operating system. Examples include the Windows Shell, the GNOME Shell, and the KDE Plasma Shell.

Functions of a Shell

Shells provide several functions, including:

• Command interpretation: Interpreting and executing user commands.
• Scripting: Writing and executing scripts to automate tasks.
• Job control: Managing multiple tasks within a single shell session.
• File manipulation: Navigating and manipulating the file system.

Popular Shells

• Bourne shell (sh)
• C shell (csh)
• Korn shell (ksh)
• Bourne Again shell (bash)
• Z shell (zsh)
• Friendly Interactive Shell (fish)

Shell Scripting

Shell scripting is writing a series of commands for the shell to execute. It is commonly used for task automation, program execution, and file manipulation. Shell scripts are typically written in a text editor and saved with a .sh extension.

Related Pages

• Operating system
• Command-line interface
• Graphical user interface
• Bourne shell
• C shell
• Korn shell
• Bash (Unix shell)
• Z shell
• fish (Unix shell)
• Shell scripting