windows os 環境變數

%SystemDrive%	C:
%SystemRoot%	C:\WINNT C:\WINDOWS
%WinDir%	C:\WINNT C:\WINDOWS
%SystemDirectory%	C:\WINNT\System32 C:\WINDOWS\System32
%ComSpec%	C:\WINNT\system32\cmd.exe
%programfiles%	C:\WINNT\Program Files
%Temp%	C:\DOCUME~1\Usr\LOCALS~1\Temp from C:\Documents and Settings\Usr\Local Settings\Temp
%Tmp%
%HOMEDRIVE%	C: The drive letter associated with the user's home directory
%HOMEPATH%	The path to the user's home directory (excluding drive): \Documents and Settings\Guest
%OS%	Windows_NT (even on Windows XP machines The operating system the user is running
%USERDOMAIN%	The name of the domain that contains the user's account
%USERNAME%	The user's name
%USERPROFILE% %USERPROFILE%\Desktop	The user's desktop folder

Variable	Sample Typical Value
%CD%	The current directory.
%DATE%	Current date in the format set by the Date command
%TIME%	Current time in the format set by the Time command
%ERRORLEVEL%	A number defining exit status of a previous command or called executable.
%RANDOM%	A random number between 0 and 32767.

sorce:
http://www.wilsonmar.com/1w2kcfg.htm