‘. ~/.bashrc’ 中第一个 ‘.’ 是什么意思？

Question 1

如果您想在 bash 中检查某些内容，请使用 type和man。

就你的情况来说，你想知道是什么。

$ type .
. is a shell builtin

shell 内置命令意味着。在里面bash shell。您可以在bash手册页中找到有关 shell 内置命令的信息。其中有一大部分Shell 内建命令

$ man bash

SHELL BUILTIN COMMANDS
       Unless otherwise noted, each builtin command documented in this section
       as accepting options preceded by - accepts -- to signify the end of the
       options.   The  :, true, false, and test builtins do not accept options
       and do not treat -- specially.  The exit, logout, break, continue, let,
       and  shift builtins accept and process arguments beginning with - with‐
       out requiring --.  Other builtins that accept  arguments  but  are  not
       specified  as accepting options interpret arguments beginning with - as
       invalid options and require -- to prevent this interpretation.
       : [arguments]
              No effect; the command does nothing beyond  expanding  arguments
              and  performing any specified redirections.  A zero exit code is
              returned.

        .  filename [arguments]
       source filename [arguments]
              Read and execute commands from filename  in  the  current  shell
              environment  and return the exit status of the last command exe‐
              cuted from filename.  If filename  does  not  contain  a  slash,
              filenames  in  PATH  are  used  to find the directory containing
              filename.  The file searched for in PATH need not be executable.
              When  bash  is  not  in  posix  mode,  the  current directory is
              searched if no file is found in PATH.  If the sourcepath  option
              to  the  shopt  builtin  command  is turned off, the PATH is not
              searched.  If any arguments are supplied, they become the  posi‐
              tional  parameters  when  filename  is  executed.  Otherwise the
              positional parameters are unchanged.  The return status  is  the
              status  of  the  last  command exited within the script (0 if no
              commands are executed), and false if filename is  not  found  or
              cannot be read.

Answer

如果您想在 bash 中检查某些内容，请使用 type和man。

就你的情况来说，你想知道是什么。

$ type .
. is a shell builtin

shell 内置命令意味着。在里面bash shell。您可以在bash手册页中找到有关 shell 内置命令的信息。其中有一大部分Shell 内建命令

$ man bash

SHELL BUILTIN COMMANDS
       Unless otherwise noted, each builtin command documented in this section
       as accepting options preceded by - accepts -- to signify the end of the
       options.   The  :, true, false, and test builtins do not accept options
       and do not treat -- specially.  The exit, logout, break, continue, let,
       and  shift builtins accept and process arguments beginning with - with‐
       out requiring --.  Other builtins that accept  arguments  but  are  not
       specified  as accepting options interpret arguments beginning with - as
       invalid options and require -- to prevent this interpretation.
       : [arguments]
              No effect; the command does nothing beyond  expanding  arguments
              and  performing any specified redirections.  A zero exit code is
              returned.

        .  filename [arguments]
       source filename [arguments]
              Read and execute commands from filename  in  the  current  shell
              environment  and return the exit status of the last command exe‐
              cuted from filename.  If filename  does  not  contain  a  slash,
              filenames  in  PATH  are  used  to find the directory containing
              filename.  The file searched for in PATH need not be executable.
              When  bash  is  not  in  posix  mode,  the  current directory is
              searched if no file is found in PATH.  If the sourcepath  option
              to  the  shopt  builtin  command  is turned off, the PATH is not
              searched.  If any arguments are supplied, they become the  posi‐
              tional  parameters  when  filename  is  executed.  Otherwise the
              positional parameters are unchanged.  The return status  is  the
              status  of  the  last  command exited within the script (0 if no
              commands are executed), and false if filename is  not  found  or
              cannot be read.

Question 2

有趣... 名称似乎是dot-command，在您的情况下，它将 .bashrc 包含到调用 shell 程序中（在您的情况下，是您的 bash 环境）。当您从命令行调用它时，它会更新您的环境变量，因为变量是在 .bashrc 中设置的。

echo "FOO=bar" > test
echo $FOO

没有结果，环境变量未设置。但是在你获取“测试”文件之后：

. test

环境变量 FOO 已设置，并且

echo $FOO

输出结果为

bar

我找到了以下信息这里：

获取文件（点命令）将代码导入脚本，并附加到脚本中（与 C 程序中的 #include 指令效果相同）。最终结果与“获取”的代码行实际存在于脚本主体中相同。当多个脚本使用公共数据文件或函数库时，这很有用。

另外，看看这个问题. 在 bash 中，.与相同source。

Answer