Another day, another PowerCLI report

Another day another reason to love PowerShell.

 I have to come up with a list of all of my Windows machines, their OS versions and editions. My first thought being nearly 100% virtualized is “WooHoo, thank you PowerCLI”…

Except that they don’t include the edition for each VM… Sad face.


However, one of my favorite elements of the PowerCLI tool is the Invoke-VMScript cmdlet contained within the VMware.VimAutomation.Core module. For more about modules, see my post Getting Started with PowerCLI. This script does exactly what it sounds like; it allows you to run a script in the guest OS. Now there’s obviously a number of pre-requisites to leveraging this tool. The big ones are as such.

  • VMtools must be running within the VM
  • You must have access to vCenter or the host where the machine resides
  • You must have Virtual Machine.Interaction.Console Interaction privilege
  • And of course you must have the necessary privileges within the VM.

There could also be some security concerns, allowing your VMware administrators the ability to run scripts within the virtual Operating System Environment, but this opens a whole other bag of worms that we’ll put aside for another conversation.

Once you’ve comfortable with the pre-req’s and any potential security elements, you can get started.

get-vm vm-vm | `
Invoke-VMScript -ScriptType Powershell -ScriptText "gwmi win32_Operatingsystem" 

So what are we doing here? We get the VM object and pipe it to the Invoke-VMScript commandlet where we are running the Powershell script “gwmi win32_Operatingsystem” within the context of the virtual OSE! What you get back is another PowerShell object containing the ExitCode of the script and the output within the ScriptOutput property.

Now just a quick sidenote. If you write powershell scripts, then inevitably you know about Get-member (aliased to: GM), but that only shows you methods and properties, not the values. If you’re not sure what you’re looking for and you’d like to see all the property elements of the object, you can just use $ObjectName|select -property * to output.

Back to the task at hand, I know I need a count of each OS type. I’d also ideally like that broken down by cluster. It would also be nice to know the machines that weren’t counted, so I can go and investigate them manually. So here we go.

$daCred=$host.ui.PromptForCredential("Please enter DA credentials","Enter credentials in the format of domainname\username","","")
foreach($objCluster in Get-Cluster){
    write-host "~~~Getting Window OS stats for $objCluster~~~"
    foreach ($objvm in $($objCluster|get-vm)){
            if ($status -eq "toolsOk" -or $status -eq "toolsOld"){
                $arrOS+=$(Invoke-VMScript -VM $objvm -ScriptType Powershell -ScriptText '$(gwmi win32_operatingsystem).caption' -GuestCredential $daCred -WarningAction SilentlyContinue).ScriptOutput
                Write-Host "Investigate VMtools status on $($objvm)   Status = $status" -BackgroundColor Red
    $arrOS|group |select count, name |ft -AutoSize -Wrap

You may say, what’s happening here? Let me tell you

After we enter in credentials that we know will work, we are going to iterate through each cluster and as we do such we are going to create an array of each OS that we find in our journey. As we iterate through each VM in the cluster we’ll check on VMtools status as we go, and if necessary flag the VM’s for check later. Then we are going to run Invoke-VMScript within a variable so that we can only capture the ScriptOutput property that’s returned within our array. Finally we can do a little sorting and counting on the array, output to the screen, and go investigate why we have so many darn red marks dirtying up our screen!


Until next time, be well!


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