PowerShell script to check whether or not there is a pending system reboot.

#Based on <http://gallery.technet.microsoft.com/scriptcenter/Get-PendingReboot-Query-bdb79542>
function Test-RebootRequired
{
    $result = @{
        CBSRebootPending =$false
        WindowsUpdateRebootRequired = $false
        FileRenamePending = $false
        SCCMRebootPending = $false
    }

    #Check CBS Registry
    $key = Get-ChildItem "HKLM:Software\Microsoft\Windows\CurrentVersion\Component Based Servicing\RebootPending" -ErrorAction Ignore
    if ($key -ne $null)
    {
        $result.CBSRebootPending = $true
    }

    #Check Windows Update
    $key = Get-Item "HKLM:SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate\Auto Update\RebootRequired" -ErrorAction Ignore
    if($key -ne $null)
    {
        $result.WindowsUpdateRebootRequired = $true
    }

    #Check PendingFileRenameOperations
    $prop = Get-ItemProperty "HKLM:SYSTEM\CurrentControlSet\Control\Session Manager" -Name PendingFileRenameOperations -ErrorAction Ignore
    if($prop -ne $null)
    {
        #PendingFileRenameOperations is not *must* to reboot?
        #$result.FileRenamePending = $true
    }

    #Check SCCM Client <http://gallery.technet.microsoft.com/scriptcenter/Get-PendingReboot-Query-bdb79542/view/Discussions#content>
    try
    {
        $util = [wmiclass]"\\.\root\ccm\clientsdk:CCM_ClientUtilities"
        $status = $util.DetermineIfRebootPending()
        if(($status -ne $null) -and $status.RebootPending){
            $result.SCCMRebootPending = $true
        }
    }catch{}

    #Return Reboot required
    return $result.ContainsValue($true)
}

##
# Usage
##

## Local Computer

if(Test-RebootRequired)
{
    Restart-Computer -Force
}

## Remote Computer

$params = @{
    ComputerName = "172.16.100.64"
    Credential = Get-Credential -UserName "localhost\Administrator" -Message "Enter Password"
    Authentication = "Default"
    ScriptBlock = ${function:Test-RebootRequired}
}

#Check Reboot is required to remote computer
$isRebootRequired = Invoke-Command @params

if($isRebootRequired -eq $true)
{
    #Restart and wait until WinRM available
    Restart-Computer -ComputerName $params.ComputerName -Credential $params.Credential -WsmanAuthentication Default -Force -Wait -For WinRM
}

#Check Reboot is required to remote computer
$isRebootRequired = Invoke-Command @params
if($isRebootRequired -eq $true)
{
    throw "Reboot required once more!"
}