Test-PendingReboot

reboot.ps1

# http://ilovepowershell.com/2015/09/10/how-to-check-if-a-server-needs-a-reboot/
function Test-PendingReboot
{
	if (Get-ChildItem "HKLM:\Software\Microsoft\Windows\CurrentVersion\Component Based Servicing\RebootPending" -EA Ignore) { return $true }
	if (Get-Item "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate\Auto Update\RebootRequired" -EA Ignore) { return $true }
	if (Get-ItemProperty "HKLM:\SYSTEM\CurrentControlSet\Control\Session Manager" -Name PendingFileRenameOperations -EA Ignore) { return $true }
	try { 
		$util = [wmiclass]"\\.\root\ccm\clientsdk:CCM_ClientUtilities"
		$status = $util.DetermineIfRebootPending()
		if(($status -ne $null) -and $status.RebootPending){
			return $true
	}
	}catch{}
	return $false
}

If (Test-PendingReboot -eq $true){
    Write-Host "Reboot is needed!"
    Restart-Computer -Confirm
}