-bash 是什么意思？

Question

我在tty1中输入命令echo $0，它返回-bash，为什么不呢bash？

Answer 1

这表明bash已作为登录 shell 启动。从man bash，部分INVOCATION（重点是我的）：

A login shell is one whose first character of argument zero is a -,  or
one started with the --login option.
...
When bash is invoked as an interactive login shell, or as a  non-inter‐
active  shell with the --login option, it first reads and executes com‐
mands from the file /etc/profile, if that file exists.   After  reading
that file, it looks for ~/.bash_profile, ~/.bash_login, and ~/.profile,
in that order, and reads and executes commands from the first one  that
exists  and  is  readable.  The --noprofile option may be used when the
shell is started to inhibit this behavior.

When a login shell exits, bash reads and  executes  commands  from   the
file ~/.bash_logout, if it exists.

$0当然是零论点。

在 Ubuntu 中，通常.profile存在并且.bash_profile不.bash_login存在。因此，登录 shell 读取.profile。

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也可以看看：

• 什么是登录和非登录 shell？
• 登录 Shell 和非登录 Shell 有什么区别？