Tail Windows Update Log Server 2016+ / Windows 10

Sometimes you have to patch mission critical Windows servers and you want to see what’s going on in the background. The modern windows update dialogue provides little verbosity, especially when compared to apt or yum in the Linux world.

In the Windows 7 / Server 2012 days I used to just tail C:\Windows\WindowsUpdate.log and watch the update process, especially when troubleshooting, or when updates were hanging on install. Nowadays if you open that file, you get the following message:

Windows Update logs are now generated using ETW (Event Tracing for Windows).
Please run the Get-WindowsUpdateLog PowerShell command to convert ETW traces into a readable WindowsUpdate.log.

For more information, please visit https://go.microsoft.com/fwlink/?LinkId=518345

As we can see, Microsoft have ditched text based logging in favour of ETW based logging. The link provided takes you to an article on Windows Update log files which lists out the various log files and what they do. If you want a concise log that is the same as what you got in Server 2012, then you have to run Get-WindowsUpdateLog which will spit out that familiar log file. This is no good in my situation, as that generated log file would be for the point in time it was generated, not a dynamically updated log file being written to during updates.

Since I don’t care really about the log contents and I just want to see some verbosity in the update process while its happening, I went through the other logs listed and came across the CBS log. CBS stands for Component based servicing and it provides output on update installation…. great!

When reviewing the log, I identified that the lines containing the strings Appl and FOD make up the majority of the hundreds, or thousands of entries, when running a tail. I filtered these out and it seems that what’s left is mostly operational logging to do with the update engine. Since my goal is to watch Windows Update progress to ensure something is happening, I wrote a quick PowerShell one liner:

Get-Content -Path $env:WinDir\Logs\CBS\CBS.log -Tail 10 -Wait | Select-String -Pattern 'Appl:|FOD:' -NotMatch

This command will get last 10 lines of the CBS log file, wait for new entries to be written, filter out Appl and FOD and write the results to the console.

If I want to get more details after patching is complete, I can always run Get-WindowsUpdateLog.

This may stop working at any point of course if Microsoft change something, but for now, it gives me peace knowing that the update stuck at 23% for 47 minutes is actually being installed and I’m not about to have a long night… or not too long anyway.

Thanks for reading – Jesse

Get Windows 10 Version Information

This morning I needed to quickly get Windows 10 version information for all workstations in a domain, so I wrote the below PowerShell script. This basic script only needed a few things to get the job done; a way to get all workstations in the domain, a way to only check computers that are online at the time, so the script doesn’t take too long with all the failures generated by offline systems, and the registry keys to determine the current OS build and minor version.

Import-Module -Name ActiveDirectory

$all_computers = Get-ADComputer -Filter * -SearchBase 'OU=computers,DC=somedomain,DC=com' | Select-Object -Property Name

$ExportPath = "$env:TEMP\$(Get-date -Format 'yyyyMMddhhmmss')_workstation_os_build_report.csv"

foreach ($c in $all_computers.name)


    if (Test-Connection -ComputerName $c -count 1 -Quiet ) {

    Write-Host "Processing $c" -ForegroundColor Cyan

    $CurrentBuild = ""
    $UBR = ""
    $OSVersion = ""
    $ComputerSystem = ""
    $props = ""
    $obj = ""

        $CurrentBuild = Invoke-Command -ComputerName $c -ScriptBlock { (Get-ItemProperty 'HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion' –Name CurrentBuild).CurrentBuild } -ErrorAction SilentlyContinue
        $UBR = Invoke-Command -ComputerName $c -ScriptBlock { (Get-ItemProperty 'HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion' –Name UBR).UBR } -ErrorAction SilentlyContinue
        $OSVersion = $CurrentBuild + "." + $UBR
        $ComputerSystem = Get-WmiObject -ComputerName $c -Class Win32_ComputerSystem -ErrorAction SilentlyContinue

       $props = [ordered]@{ 
        'HostName' = $ComputerSystem.Name;
        'OSVerion' = $OSVersion
        $obj = New-Object -TypeName PSObject -Property $props

    Write-Output $obj | Export-Csv -Path $ExportPath -NoTypeInformation -Append -NoClobber -Force
    else {
        Write-Host "$c is offline..." -ForegroundColor Green

Write-Host "Output csv file is located here: `n `n $ExportPath `n" -ForegroundColor Yellow

Obviously there are a few issues with this script. It won’t get systems that are turned off, PowerShell remoting needs to be enabled/working, and in a large domain, it’s probably going to take a long time without some sort of parallelisation or a more efficient way of querying each host…. regardless, this was just a quick indicator for me of the general patch levels of systems in the domain.

Code also on my github here.

Thanks for reading – Jesse