判断文件是否存在（exist）

set datedir=%date:~0,4%%date:~5,2%%date:~8,2%
if exist d:\rollback\%datedir%\Server\ (rename d:\rollback\%datedir%\Server Server_0)
xcopy /e /h /r /s D:\Server\\*.* "d:\rollback\%datedir%\Server\"