Query computers for windows update status. Now writes out warnings for computers needing patches.

Get-WindowsUpdateStatus.ps1

<#

.EXAMPLE
    Get-WindowsUpdateStatus -ComputerName ('Server01.test.local,'Server02.test.local')

    ComputerName HasPendingUpdates Updates
    ------------ ----------------- -------
    Server01                 False {}     
    Server01                 False {}  

.EXAMPLE 
    Get-WindowsUpdateStatus -DiscoverDomainComputers 
    
    WARNING: Server03 requires 9 updates

    ComputerName   HasPendingUpdates Updates                                                                                                                                     
    ------------   ----------------- -------                                                                                                                                     
    Server01                   False {}                                                                                                                                          
    Server02                   False {}                                                                                                                                                                                                                                                                                  
    Server03                    True {@{T...

#>
Function Get-WindowsUpdateStatus{
  [cmdletbinding(DefaultParameterSetName='computername')]
  param(
    [parameter(ValueFromPipeline=$true,ParameterSetName='computername')]
    [string[]]
    $ComputerName = $env:COMPUTERNAME,

    [switch]
    [parameter(Mandatory=$true,ParameterSetName='discover')]
    $DiscoverDomainComputers
  )   

  begin{
    if($DiscoverDomainComputers){
        $Domain = Get-ADDomain
        [string[]] $clusters = Get-Cluster -Domain $Domain.DNSRoot
        $AllDomainComputers = Get-ADComputer -Filter {Name  -like "*" } | Where-Object { $_.Name -notin $clusters}
        $ComputerName =$AllDomainComputers.DnsHostName
    }
    
    $script:ServerUpdateStatus = {
      $Query = "IsInstalled=0"
      $Searcher = New-Object -ComObject Microsoft.Update.Searcher
      $SearchResult = $Searcher.Search($Query).Updates
      $BasicUpdateInfo =@(
          'Title'
          @{Name='KBArticleIDs';Expression={[string[]]$_.KBArticleIDs}}
          @{Name='Categories';Expression={$_.Categories | Select-Object -Property ('Name','Description')}}
          'RebootRequired'
      )
      $DetailedUpdateInfo = @(
          'Title'
          @{Name='KBArticleIDs';Expression={[string[]]$_.KBArticleIDs}}
          @{Name='Categories';Expression={$_.Categories | Select-Object -Property ('Name','Description')}}
          'Description'
          'IsDownloaded'
          'IsInstalled'
          'IsMandatory'
          'IsUninstallable'
          'UninstallationNotes'
          'RebootRequired'
          @{Name='BundledUpdates';Expression={$_.BundledUpdates | Select-Object -Property $BasicUpdateInfo }}
      )
      
      if($SearchResult.Count -ne 0){
        Write-Warning -Message "$env:COMPUTERNAME requires $($SearchResult.Count) updates"
      } else {
        Write-Verbose -Message  "$env:COMPUTERNAME does not require patches."
      }

      # This ensures the property is a collection, even when empty.
      # That means $Updates[0].Updates.Count will always work.
      $Updates = @()
      $Updates += ($SearchResult | Select-Object -Property $DetailedUpdateInfo )

      [pscustomobject]@{
          ComputerName = $env:COMPUTERNAME
          HasPendingUpdates= ($SearchResult.Count -ne 0)
          Updates = $Updates 
      }
    }
  }
  process{  
    
    # Invoke-Command can be finicky when targeting the localhost, so just skip that and run directly.
    # Using -icontains and -inotin to be explictly case insensitive.
    if($ComputerName -icontains $env:COMPUTERNAME -or 
        $ComputerName -icontains "$env:computername.$env:userdnsdomain" -or 
        $ComputerName -icontains "localhost"
        ){
        & $script:ServerUpdateStatus
    }
    # Now just remove localhost
    [string[]]$RemoteServers = $ComputerName | 
      Where-Object {$_ -inotin @($env:COMPUTERNAME,"$env:computername.$env:userdnsdomain","localhost")}
    
    if($RemoteServers.Count -gt 0){
        $commandParameters = @{
          ComputerName= $RemoteServers
          ScriptBlock = $script:ServerUpdateStatus
        }
        Invoke-Command @commandParameters |     Select-Object -Property ('ComputerName','HasPendingUpdates','Updates')      
    }
  }

}