@echo off
for /f "tokens=1-4 delims=/ " %%i in ("%date%") do (
    set dow=%%i
    set month=%%j
    set day=%%k
    set year=%%l
)
set datestr=%year%-%month%-%day%
echo datestr is %datestr%

set BACKUP_FILE=BACKUP_%datestr%
echo backup file name is %BACKUP_FILE%