在 windows 环境下，emacs 的配置目录可以通过下面几种方式来设置：
- If the environment variableHOME is set, use the directory it indicates.
- If the registry entry HKCU\SOFTWARE\GNU\Emacs\HOME is set, use the directory it indicates.
- If the registry entry HKLM\SOFTWARE\GNU\Emacs\HOME is set, use the directory it indicates. Not recommended, as it results in users sharing the same HOME directory.
- If C:.emacs exists, then use C:/. This is for backward compatibility, as previous versions defaulted to C:/ if HOME was not set.
- Use the user's AppData directory, usually a directory called Application Data under the user's profile directory, the location of which varies according to Windows version and whether the computer is part of a domain.
HOME 是 String 类型的值。
然后运行 bin\runemacs.exe 就可以打开 emacs 了。