TEE.bat

@ECHO OFF
SETLOCAL
 SET Append=false
IF /I "%~1]=="/a" ( SET Append=true & SHIFT )
IF "%~1"== "" GOTO help
IF "%~2"== "" GOTO help
 SET Counter=0
FOR /F %%A IN ('DIR /A /B %1 2^>NUL') DO CALL :Count "%%~fA"
 IF %Counter% GTR 1 ( SET Counter= & GOTO Syntax )
 SET File=%1
 DIR /AD %File% >NUL 2>NUL
 IF NOT ERRORLEVEL 1 ( SET File= & GOTO Syntax )
 SET Y=
VER | FIND "Windows NT" > NUL
IF ERRORLEVEL 1 SET Y=/Y
 IF %Append%==false  (COPY %Y% NUL %File% > NUL 2>&1)
 FOR /F "tokens=1* delims=]" %%A IN ('FIND /N /V ""') DO (
    > CON ECHO.%%B
        >> %File% ECHO.%%B
 )
ENDLOCAL
GOTO:EOF
 :Count
SET /A Counter += 1
 SET File=%1
GOTO:EOF
 :help
 ECHO.
 ECHO Display text on screen and redirect it to a file simultaneously ECHO Usage: some_command ^| TEE.BAT [ /a ] filename
 ECHO.
ECHO Where: "some_command" is the command whose output should be redirected
 ECHO "filename" is the file the output should be redirected to
 ECHO /a appends the output of the command to the file,
 ECHO rather than overwriting the file
 ECHO.
ECHO Made by Wasif Hasan. Nov 2019
Usage: command | tee