Create If Statement For Checking Registry Value

Question

I'm working on a script to edit registry values to enable right-clicking of msi files to run as administator. That involves adding a subkey at:

HKCR:\msi.package\shell

to get

HKCR:\msi.package\shell\runas

Then adding a value to runas called

HasLUAShield

And another subkey to runas to get:

HKCR:\Msi.Package\shell\runas\command

With a value of

C:\Windows\System32\msiexec.exe /i \"%1\" %*

I've been able to successfully create them, but my hope is to first check to see if they are there before adding them. I know I can check both:

Test-Path -Path HKCR:\Msi.Package\shell\runas

and

Test-Path -Path HKCR:\Msi.Package\shell\runas\command

But checking the value of HasLUAShield is getting a bit more difficult. I've found I can get it in a list of values with:

Get-ItemProperty -Path 'HKCR:\msi.package\shell\runas'

But I can't figure out how to check for just the HasLUAShield and figure out a way to add it to an if statement to determine if I need to add the value or not. Anyone have a suggestion? I've also tried:

Get-ItemPropertyValue -Path 'HKCR:\msi.package\shell\runas' -Name HasLUAShield

But that returns nothing.

Answer 1

You don't really need Get-ItemPRoperty or Get-ItemPropertyValue becasue the value has no data -- it's mere existence serves as a flag. The RegistryKey object returned by Get-Item <KeyPath> has a NotePropety named "Property" that is a String[] of the values under the key:

PS C:\> (Get-Item HKCR:\batfile\Shell\runas).Property
HasLUAShield

So soemthing like:

$keyPath = HKCR:\Msi.Package\Shell\runas
$keyValue = 'HasLUAShield'
$command = '\System32\msiexec.exe /i "%1" %*'

If ( ! (Test-Path $keyPath))
{
    # runas key doesn't exist -> create it.
}
$key = Get-Item $keyPath
If ($keyValue -notIn $key.Property )
{
    New-ItemProperty -Path $keyPath -Name $keyValue
}
If ( ! (Test-Path "$keyPath\Command"))
{
    # "Command" subkey doesn't exist -- create it
}
$splat = @{
    'Path'  = "$keyPath\Command"
    'Name'  = '(Default)'
}
If ((Get-ItemPropertyValue $splat) -notMatch [Regex]::Escape("$env:SystemRoot$command"))
{
    Set-ItemProperty $splat -Value "%SystemRoot%$Command" -Type ExpandString
}