有哪些 shell 需要了解 ？

sh

The Bourne shell (sh) is a shell command-line interpreter for computer operating systems.

The Bourne shell was the default shell for Version 7 Unix. Unix-like systems continue to have /bin/sh—which will be the Bourne shell, or a symbolic link or hard link to a compatible shell—even when other shells are used by most users.

Developed by Stephen Bourne at Bell Labs, it was a replacement for the Thompson shell, whose executable file had the same name—sh. It was released in 1979 in the Version 7 Unix release distributed to colleges and universities. Although it is used as an interactive command interpreter, it was also intended as a scripting language and contains most of the features that are commonly considered to produce structured programs.

It gained popularity with the publication of The Unix Programming Environment by Brian Kernighan and Rob Pike—the first commercially published book that presented the shell as a programming language in a tutorial form.

来源自 Wikipedia：https://en.wikipedia.org/wiki/Bourne_shell

bash

overview

1. Bash is a Unix shell and command language written by Brian Fox for the GNU Project as a free software replacement for the Bourne shell (sh).
2. First released in 1989, it has been used as the default login shell for most Linux distributions.
3. Bash was one of the first programs Linus Torvalds ported to Linux, alongside GCC.
4. A version is also available for Windows 10 and Windows 11 via the Windows Subsystem for Linux.
5. It is also the default user shell in Solaris 11. Bash was also the default shell in versions of Apple macOS from 10.3 (originally, the default shell was tcsh) to 10.15 (macOS Catalina), which changed the default shell to Z shell (zsh), although Bash remains available as an alternative shell.

how to use and supported functions 使用方式和支持的功能

1. Bash is a command processor that typically runs in a text window where the user types commands that cause actions.
2. Bash can also read and execute commands from a file, called a shell script.
3. Like most Unix shells, it supports filename globbing (wildcard matching), piping, here documents, command substitution, variables, and control structures for condition-testing and iteration.
4. The keywords, syntax, dynamically scoped variables and other basic features of the language are all copied from sh. Other features, e.g., history, are copied from csh and ksh.
5. Bash is a POSIX-compliant shell, but with a number of extensions.

origin of name 名字的由来

The shell’s name is an acronym (首字母缩拼词) for Bourne Again Shell, a pun (双关语) on the name of the Bourne shell that it replaces and the notion (概念) of being “born again”.

famous historical event/gossip 著名的历史事件/八卦

A security hole in Bash dating from version 1.03 (August 1989), dubbed (被称为) Shellshock, was discovered in early September 2014 and quickly led to a range of attacks across the Internet. Patches (补丁) to fix the bugs were made available soon after the bugs were identified (发现/确认).

来源自Wikipedia：https://en.wikipedia.org/wiki/Bash_(Unix_shell)

Z shell

1. The Z shell (Zsh) is a Unix shell that can be used as an interactive login shell and as a command interpreter for shell scripting.

2. Zsh is an extended Bourne shell with many improvements, including some features of Bash, ksh, and tcsh.

3. Zsh was created by Paul Falstad in 1990 while he was a student at Princeton University. It combines features from both ksh and tcsh, offering functionality such as programmable command-line completion, extended file globbing (文件通配), improved variable/array handling, and themeable prompts (主题化提示).

4. Zsh is available for Microsoft Windows as part of the UnxUtils collection and has been adopted as the default shell for macOS Catalina and Kali Linux.

5. The “Oh My Zsh” user community website provides a platform for third-party plug-ins and themes, featuring a large and active contributor base (拥有庞大而活跃的贡献者基础).

来源自Wikipedia: https://en.wikipedia.org/wiki/Z_shell