可以用CMD的SET命令来查看现有的系统变量，“="前的部分用%括起来就是。
常用：
%USERPROFILE%
=C:\Users\用户名
%SystemRoot%
=C:\WINDOWS
%SystemDrive%
=C:
%APPDATA%
=C:\Users\用户名\AppData\Roaming
%LOCALAPPDATA%
=C:\Users\用户名\AppData\Local
%windir%
=C:\WINDOWS
%Path%
=C:\Windows\system32;C:\Windows;
%ProgramData%
=C:\ProgramData
%ProgramFiles%
=C:\Program
Files
%ProgramFiles(x86)%
=C:\Program
Files
(x86)
其他：
%ALLUSERSPROFILE%
=C:\ProgramData
%CommonProgramFiles%
=C:\Program
Files\Common
Files
%CommonProgramFiles(x86)%
=C:\Program
Files
(x86)\Common
Files
%CommonProgramW32%
=C:\Program
Files\Common
Files
%COMPUTERNAME%
=MyPC
%ComSpec%
=C:\WINDOWS\system32\cmd.exe
%HOMEDRIVE%
=C:
%HOMEPATH%
=\Users\用户名
%LOGONSERVER%
=\\MicrosoftAccount
%OS%
=Windows_NT
%ProgramW32%
=C:\Program
Files
%PUBLIC%
=C:\Users\Public
%TEMP%
=C:\Users\用户名\AppData\Local\Temp
%TMP%
=C:\Users\用户名\AppData\Local\Temp
%USERDOMAIN%
=MyPC
%USERNAME%
=用户名
