PowerShell: Turn off computer screen

turn-off-screen.ps1

# Source: http://www.powershellmagazine.com/2013/07/18/pstip-how-to-switch-off-display-with-powershell/

# Turn display off by calling WindowsAPI.
 
# PostMessage(HWND_BROADCAST,WM_SYSCOMMAND, SC_MONITORPOWER, POWER_OFF)
# HWND_BROADCAST  0xffff
# WM_SYSCOMMAND   0x0112
# SC_MONITORPOWER 0xf170
# POWER_OFF       0x0002
 
Add-Type -TypeDefinition '
using System;
using System.Runtime.InteropServices;
 
namespace Utilities {
   public static class Display
   {
      [DllImport("user32.dll", CharSet = CharSet.Auto)]
      private static extern IntPtr PostMessage(
         IntPtr hWnd,
         UInt32 Msg,
         IntPtr wParam,
         IntPtr lParam
      );
 
      public static void PowerOff ()
      {
         PostMessage(
            (IntPtr)0xffff, // HWND_BROADCAST
            0x0112,         // WM_SYSCOMMAND
            (IntPtr)0xf170, // SC_MONITORPOWER
            (IntPtr)0x0002  // POWER_OFF
         );
      }
   }
}
'

[Utilities.Display]::PowerOff()

You can also use this command line command based on code above:

powershell.exe (Add-Type '[DllImport("user32.dll")]^public static extern int PostMessage(int hWnd, int hMsg, int wParam, int lParam);' -Name a -Pas)::PostMessage(0xffff,0x0112,0xF170,0x0002)