批处理按日期备份文件夹

@echo off

set YYYYmmdd=%date:~0,4%%date:~5,2%%date:~8,2%
set "filename=E:\download\bak\%YYYYmmdd%"

if not exist %filename%  mkdir %filename%


xcopy.exe E:\download\src %filename% /e/r/h/y

exit