本文共 921 字，大约阅读时间需要 3 分钟。
1.
Bash is the shell, or command language interpreter, that will appear in the GNU operating system. Bash is an sh-compatible shell that incorporates useful features from the Korn shell (ksh) and C shell (csh).
Dash(Debian Almquist shell ) is a POSIX-compliant implementation of /bin/sh that aims to be as small as possible. It does this without sacrificing speed where possible. In fact, it is significantly faster than bash (the GNU Bourne-Again SHell) for most tasks.
2.
Ubuntu 的默认Shell是 Dash,
Bash 和 Dash两者语法是有区别的，详见
例如
bash: 支持两者
| 1 2 3 4 5 6 | igi@gentoo ~ $ [ 'a' = 'a' ] && echo 'equal' equal igi@gentoo ~ $ [ 'a' == 'a' ] && echo 'equal' equal igi@gentoo ~ $ echo $0 /bin/bash |
dash: 只支持=
| 1 2 3 4 5 6 7 | $ [ 'a' = 'a' ] && echo 'equal' equal $ [ 'a' == 'a' ] && echo 'equal' [: 2: a: unexpected operator $ echo $0 dash $ |
3.
如果Shell是从别的linux平台移植到Ubuntu, 应将 /bin/sh 改成bash
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