Force Windows Automatic Updates with PowerShell

#      Script: WSUS.ps1
#      Author: Gregory Strike
#         URL: //www.gregorystrike.com/2011/04/07/force-windows-automatic-updates-with-powershell/
#        Date: 02-19-2010
# Information: This script was adapated from the WUA_SearchDownloadInstall.vbs VBScript from Microsoft.  It uses the
#              Microsoft.Update.Session COM object to query a WSUS server, find applicable updates, and install them.
#
#              WSUS.ps1 is a little less verbose about what it is doing when compared to the orginal VBScript.  The
#              lines exist in the code below to show the same information as the original but are just commented out.
#
#              WSUS.ps1 can automatically install applicable updates by passing a Y to the script.  The default
#              behavior is to ask whether or not to install the new updates.
#
#              Syntax:  .\WSUS.ps1 [Install] [Reboot]
#                       Where [Install] is optional and can be "Y", "Yes", "No" or "N"
#                       Whether or not to install the updates automatically.  If Null, the user will be prompted.
#
#                       Where [Reboot] is optional and can be "Y", "Yes", "No" or "N",  This
#                       If updates require a reboot, whether or not to reboot automatically.  If Null, the user will
#                       be prompted.
#
#      Update: 5/30/2012 - Fixed the "Privilege not held" error that caused script to fail when requesting a reboot.

$UpdateSession = New-Object -Com Microsoft.Update.Session
$UpdateSearcher = $UpdateSession.CreateUpdateSearcher()

Write-Host("Searching for applicable updates...") -Fore Green

$SearchResult = $UpdateSearcher.Search("IsInstalled=0 and Type='Software'")

Write-Host("")
Write-Host("List of applicable items on the machine:") -Fore Green
For ($X = 0; $X -lt $SearchResult.Updates.Count; $X++){
    $Update = $SearchResult.Updates.Item($X)
    Write-Host( ($X + 1).ToString() + "> " + $Update.Title)
}

If ($SearchResult.Updates.Count -eq 0) {
    Write-Host("There are no applicable updates.")
    Exit
}

#Write-Host("")
#Write-Host("Creating collection of updates to download:") -Fore Green

$UpdatesToDownload = New-Object -Com Microsoft.Update.UpdateColl

For ($X = 0; $X -lt $SearchResult.Updates.Count; $X++){
    $Update = $SearchResult.Updates.Item($X)
    #Write-Host( ($X + 1).ToString() + "> Adding: " + $Update.Title)
    $Null = $UpdatesToDownload.Add($Update)
}

Write-Host("")
Write-Host("Downloading Updates...")  -Fore Green

$Downloader = $UpdateSession.CreateUpdateDownloader()
$Downloader.Updates = $UpdatesToDownload
$Null = $Downloader.Download()

#Write-Host("")
#Write-Host("List of Downloaded Updates...") -Fore Green

$UpdatesToInstall = New-Object -Com Microsoft.Update.UpdateColl

For ($X = 0; $X -lt $SearchResult.Updates.Count; $X++){
    $Update = $SearchResult.Updates.Item($X)
    If ($Update.IsDownloaded) {
        #Write-Host( ($X + 1).ToString() + "> " + $Update.Title)
        $Null = $UpdatesToInstall.Add($Update)
    }
}

$Install = [System.String]$Args[0]
$Reboot  = [System.String]$Args[1]

If (!$Install){
    $Install = Read-Host("Would you like to install these updates now? (Y/N)")
}

If ($Install.ToUpper() -eq "Y" -or $Install.ToUpper() -eq "YES"){
    Write-Host("")
    Write-Host("Installing Updates...") -Fore Green

    $Installer = $UpdateSession.CreateUpdateInstaller()
    $Installer.Updates = $UpdatesToInstall

    $InstallationResult = $Installer.Install()

    Write-Host("")
    Write-Host("List of Updates Installed with Results:") -Fore Green

    For ($X = 0; $X -lt $UpdatesToInstall.Count; $X++){
        Write-Host($UpdatesToInstall.Item($X).Title + ": " + $InstallationResult.GetUpdateResult($X).ResultCode)
    }

    Write-Host("")
    Write-Host("Installation Result: " + $InstallationResult.ResultCode)
    Write-Host("    Reboot Required: " + $InstallationResult.RebootRequired)

    If ($InstallationResult.RebootRequired -eq $True){
        If (!$Reboot){
            $Reboot = Read-Host("Would you like to reboot now? (Y/N)")
        }

        If ($Reboot.ToUpper() -eq "Y" -or $Reboot.ToUpper() -eq "YES"){
            Write-Host("")
            Write-Host("Rebooting...") -Fore Green
            $WMIReboot = Get-WMIObject -Class Win32_OperatingSystem
            $WMIReboot.PSBase.Scope.Options.EnablePrivileges = $True
            $WMIReboot.Reboot()
        }
    }
}