DOS比較演算子（LSS,LEQ,GTR,GEQ,EQU,NEQ)

:: DateDel.bat - Demonstrates deletion of files modified before 7 days ago (including the 7th day)
:: Will Sort - 2021-8-26 - CMD@WinXP
:: Note: Do not place this batch file in the directory where you need to select files for deletion
:: The program only demonstrates the deletion, if the demonstration is correct, delete the echo in front of del and it will be executed normally.
:: If the first execution date is not 2021-8-26, you need to adjust the reserved date list in the fourth line of code
:: The program needs to be run at least once a day to automatically update the date list
@echo off
if "%1"==":" goto %2
if exist %temp%. \_DateDel.bat %temp%. \_DateDel.bat
%0 : Update 2021-08-20 2021-08-21 2021-08-22 2021-08-23 2021-08-24 2021-08-25 2021-08-26

:Update
setlocal EnableExtensions
set today=%date:~0,10%
if not "%today%"=="%9" %0 : Update %4 %5 %6 %7 %8 %9 %today%
echo %0 : Update %3 %4 %5 %6 %7 %8 %9 >%temp%. \_DateDel.bat

:Delete
for /r %%f in (*. *) do if "%%~tf" LEQ "%3" echo del "%%f"

:End

if %day% GTR 31 (
set /a day=1 
set /a month=month+1)