timed_shutdown.bat

@echo off
set /p targetInput=HH:MM:SS:

for /f "tokens=1-4 delims=:" %%A in ("%targetInput%") do (
    set targetHour=%%A
    set targetMinute=%%B
    set targetSecond=%%C
)

if "%targetSecond%"=="" (
    set targetSecond=0
)

if %targetHour% gtr 23 (
    echo Hour error
    goto :eof
)

if %targetMinute% gtr 59 (
    echo Minute error
    goto :eof
)

if %targetSecond% gtr 59 (
    echo Second error
    goto :eof
)

for /f "tokens=1-4 delims=:. " %%A in ('time /t ^& echo %time%') do (
    set hour=%%A
    set minute=%%B
    set second=%%C
)

set /a currentTime=%hour%*3600 + %minute%*60 + %second%
set /a targetTime=%targetHour%*3600 + %targetMinute%*60 + %targetSecond%

if %currentTime% GEQ %targetTime% (
    set /a remainingSeconds=86400 - %currentTime% + %targetTime%
) else (
    set /a remainingSeconds=%targetTime% - %currentTime%
)

shutdown -s -t %remainingSeconds%
pause
shutdown -a