Shows a dialog to shut down the computer in a specified time.

Shutdown.bat

@echo off

setlocal
 
REM Generic .bat file to launch .ps1 files.
REM Name the .bat file like the .ps1 file and you are done.
 
set this_file_no_extension=%~n0
set ps1_file=%this_file_no_extension%.ps1
 
powershell.exe -ExecutionPolicy Bypass -NoLogo -WindowStyle Hidden -NoProfile -File %ps1_file%

endlocal

Shutdown.ps1

# ---------------------------------------------------------------------
# Script: Shutdown.ps1
# Author: Jonas Gröger <jonas.groeger@gmail.com>
# Date: 12.04.2014
# Keywords: Shutdown, Timer, Minutes
# Comments: Reads a number of minutes from the command line and shuts
#           down after that time.
# ---------------------------------------------------------------------

$minutes = 0

[void][System.Reflection.Assembly]::LoadWithPartialName('Microsoft.VisualBasic')

do {
	$input = [Microsoft.VisualBasic.Interaction]::InputBox('In how many minutes should I shut down?', "Shutdown", 0)
	
	# User pressed cancel
	if (!$input) {
		Exit
	}
	$no_number = ![int]::TryParse($input, [ref]$minutes)
	$below_zero = $minutes -lt 0
} while($no_number -or $below_zero)

$seconds = $minutes * 60

shutdown /s /f /t $seconds /c "Shutting down the computer in $seconds seconds ($minutes minutes)."