PowerShell logon script to log Microsoft Office version

Question

I came across PowerShell script to log Microsoft Office version of remote computer on domain. I want to run it as logon script to I modified OpenRemoteBaseKey to OpenBaseKey and this is the code:

$version = 0
$reg = [Microsoft.Win32.RegistryKey]::OpenBaseKey('LocalMachine', 'Default')

$reg.OpenSubKey('software\Microsoft\Office').GetSubKeyNames() |% {
  if ($_ -match '(\d+)\.') {
    if ([int]$matches[1] -gt $version) {
      $version = $matches[1]
    }
  }    
}

if ($version) {
    Add-Content -Path \\server\share\oversion.txt -Value "$env:computername $env:username : $version"
}
else {
    Add-Content -Path \\server\share\oversion.txt -Value "$env:computername $env:username : 0"
}

but now I receive error:

You cannot call a method on a null-valued expression.
At line:4 char:1
+ $reg.OpenSubKey('software\Microsoft\Office').GetSubKeyNames() |% {
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (:) [], RuntimeException
    + FullyQualifiedErrorId : InvokeMethodOnNull

but not sure what this means since GetSubKeyNames seems valid: https://docs.microsoft.com/en-us/dotnet/api/microsoft.win32.registrykey.getsubkeynames?view=netframework-4.7.2 , also it works with OpenRemoteBaseKey , can someone point me to right direction, please?

Answer 1

I'm not sure why OpenRemoteBaseKey works, but OpenBaseKey doesn't because I cannot reproduce that..
You might however try the more Powershell way of doing this:

$version = 0
Get-ChildItem -Path 'HKLM:\SOFTWARE\Microsoft\Office' -Name | Where-Object {$_ -match '(\d+)\.\d+'} | ForEach-Object {
    $version = [math]::Max([int]$_, $version)
}
Add-Content -Path \\server\share\oversion.txt -Value "$env:COMPUTERNAME $env:USERNAME : $version"