取年份：echo %date:~0,4%
取月份：echo %date:~5,2%
取日期：echo %date:~8,2%
取星期：echo %date:~10,6%
取小时：echo %time:~0,2%
取分钟：echo %time:~3,2%
取秒：echo %time:~6,2%
取毫秒：echo %time:~9,2%

echo BAK%date:~0,4%%date:~5,2%%date:~8,2%%time:~0,2%%time:~3,2%%time:~6,2%%time:~9,2%
得到的就是：
BAK2016110512354001 这个样子