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Difference between Thompson Shell and POSIX Shell

Last Updated : 24 Apr, 2023
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Introduction :

Thompson Shell, also known as sh, was the first Unix shell created by Ken Thompson in the early 1970s. It was designed to be a small, simple, and fast shell with a limited number of features. The Thompson Shell is no longer in use today and has been replaced by more advanced shells such as the POSIX Shell.

The POSIX Shell, also known as sh, is a standard Unix shell that conforms to the POSIX (Portable Operating System Interface) standard. It is a more advanced shell compared to the Thompson Shell and provides a wide range of features, including command history, job control, and shell scripting. The POSIX Shell is the default shell for most Unix-based systems and is still widely used today.

1. Thompson Shell : Thompson Shell is the first Unix shell which was introduced by Ken Thompson. It was a simple command interpreter which introduced several innovative features to the command-line interface. This command shell led to the development of the later Unix Command shells. It was not designed for scripting. It was developed at AT&T Bell Laboratories. It was released in 1971.

 2. POSIX Shell : POSIX Shell is a command line shell for computer operating system which was introduced by IEEE Computer Society. POSIX stands for Portable Operating System Interface. POSIX Shell is based on the standard defined in Portable Operating System Interface (POSIX) – IEEE P1003.2. It is considered as one of the primary shell in scripts. It was released in 1992. 
Difference between Thompson Shell and POSIX Shell :

S.No. THOMPSON SHELL POSIX SHELL
1. It was developed by Ken Thompson at AT&T Bell Laboratories. It was developed by IEEE Computer Society.
2. It was released in 1971. It was released in 1992.
3. It is the first Unix shell. It is one of the primary shell.
4. Its usual environment is Unix. It usual environment is POSIX.
5. It does not have license. It has IEEE standard license.
6. It does not have unicode support. It current version has unicode support.
7. It does not have stream redirection. It has stream redirection for arbitrary fds.
8. It is used as command line interpreter only. It is used as command line interpreter as well as scripting language.
9. It does not have command history. It current version has command history.
10. It does not have value prompt. It has value prompt.
11. Created by Ken Thompson Provides more features
12. Small, simple, and fast Command history
13. Limited number of features Job control
 
14. No longer in use  Default shell for most Unix-based systems
 
15. Basic shell  Shell scripting support

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