%date:~0,4%%date:~5,2%%date:~8,2%.data

 

ex:

 

"%systemdrive%\Program Files\Common Files\Microsoft Shared\web server extensions\14\BIN\stsadm.exe" -o backup -url http://cqsps/ -filename "e:\backup\80%date:~0,4%%date:~5,2%%date:~8,2%.data" -overwrite

echo. & pause