Shell programs, often referred to as “shells,” provide a command-line interface (CLI) for interacting with an operating system. They interpret user-entered commands and scripts, and they execute system utilities or programs.
Here are some of the prominent shell programs:
- Bash (Bourne Again Shell):
- It’s an extension of the original Bourne Shell (
sh) and is present by default on many Linux distributions and macOS. It supports scripting, command substitution, variables, functions, and control flow constructs.
- It’s an extension of the original Bourne Shell (
- Zsh (Z Shell):
- A highly interactive shell that includes many features from other shells, including bash and tcsh. It has an enhanced auto-completion, command correction, and a sophisticated scripting language.
- Fish (Friendly Interactive Shell):
- Known for its user-friendly design and features like advanced autosuggestions, syntax highlighting, and web-based configuration.
- Tcsh (TENEX C Shell):
- An enhanced C shell, with syntax similar to that of the C programming language. It includes scripting capabilities, command-line editing, and job control.
- Ksh (KornShell):
- Developed by David Korn, this shell incorporates features from C shell and Bourne shell. It is known for its compatibility with the Bourne shell and includes additional features to enhance script writing and execution.
- PowerShell:
- Developed by Microsoft, PowerShell is a task automation and configuration management framework that includes a command-line shell and scripting language. It is built on the .NET Common Language Runtime (CLR) and accepts and returns .NET objects, different from traditional text shell interfaces.
- DASH (Debian Almquist Shell):
- A lightweight shell optimized for performance. It’s often used in environments where system resources are scarce.
- Csh (C Shell):
- A shell with a syntax resembling that of the C programming language. Though not as popular or widely used as other shells, it has been influential in the design of later shells.
Each of these shells offers a unique set of features, and the choice between them may come down to personal preference or the specific needs of a task. They provide the foundation for very powerful system interaction and scripting capabilities, enabling users to automate tasks, manage files, and much more.