The sh shell, also known as the Bourne shell, is one of the oldest and most widely used command-line interpreters in Unix-based systems. Developed by Stephen Bourne at AT&T’s Bell Labs, it was first released in 1979 as the default shell for Unix Version 7. The sh shell provides a simple and efficient environment for executing commands, scripting, and automating tasks. It is known for its portability and is available on virtually all Unix-like operating systems, making it a reliable choice for system administrators and developers.
The sh shell supports basic control structures such as loops and conditionals, as well as functions and variables. It also allows for input/output redirection and piping, enabling users to create complex command sequences. While it lacks some of the advanced features found in more modern shells like bash or zsh, the sh shell remains a fundamental tool for scripting and system administration.
| Feature | sh (Bourne Shell) | bash (Bourne Again Shell) | zsh (Z Shell) |
|---|---|---|---|
| Release Year | 1979 | 1989 | 1990 |
| Developer | Stephen Bourne | Brian Fox | Paul Falstad |
| Scripting Capabilities | Basic | Advanced | Advanced |
| Interactive Features | Minimal | Extensive | Extensive |
| Customization | Limited | High | Very High |
| Portability | Very High | High | Moderate |
| Default Shell on | Unix Version 7 | Most Linux distributions | Some Linux distributions |
| Job Control | No | Yes | Yes |
| Command History | No | Yes | Yes |
| Tab Completion | No | Yes | Yes |
The table above highlights some of the key differences between the sh shell and more modern alternatives like bash and zsh. While sh is highly portable and provides essential scripting capabilities, bash and zsh offer more advanced features, better interactivity, and greater customization options. These enhancements make bash and zsh more suitable for interactive use and complex scripting tasks, whereas sh remains a solid choice for simple scripts and compatibility across different Unix-like systems.