1. 汤普森壳牌：
Thompson Shell 是第一个由Ken Thompson引入的 Unix shell。这是一个简单的命令解释器，它为命令行界面引入了几个创新功能。这个命令外壳导致了后来的 Unix 命令外壳的发展。它不是为脚本设计的。它是在AT&T 贝尔实验室开发的。它于 1971 年发行。
2. POSIX 外壳：
POSIX Shell 是 IEEE 计算机协会推出的计算机操作系统的命令行 shell。 POSIX 代表便携式操作系统接口。 POSIX Shell 基于便携式操作系统接口 (POSIX) – IEEE P1003.2 中定义的标准。它被认为是脚本中的主要 shell 之一。它于1992年发布。
Thompson Shell 和 POSIX Shell 的区别：
| 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. |