Powershell bitlocker check

Question

Hi im having diffeculties to get my script working: It keeps failing on the first write output, even when the powershell version is higher then 4. It only works when I remove And $winver -eq $os1 -or $os2 -or $os3.

Otherwise it keeps telling me my powershell version needs to be upgraded. Im on V5 currently and $PSVersionTable.PSVersion.Major does says it 5 indeed. What am i doing wrong?

    $winver = (Get-WmiObject -class Win32_OperatingSystem).Caption
$powershellversion = $PSVersionTable.PSVersion.Major
$os1 = "Microsoft Windows 7 Professional"
$os2 = "Microsoft Windows 10 Pro"
$os3 = "Microsoft Windows 10 Enterprise"

if($winver -ne ($os1, $os2, $os3) -contains $winver){
    Write-Host "Bitlocker not supported on $winver"
    Exit 0
}

if($powershellversion -lt 4){
    Write-Host "Upgrade Powershell Version"
    Exit 1010
}
else
{

$bitlockerkey = (Get-BitLockerVolume -MountPoint C).KeyProtector.RecoveryPassword
$pcsystemtype = (Get-WmiObject -Class Win32_ComputerSystem).PCSystemType
if ($pcsystemtype -eq "2"){
$setsystemtype = "Laptop"
}
else {
$setsystemtype = "Desktop"
}

if ($setsystemtype -eq "laptop" -And $bitlockerkey -eq $null  -and ($os1, $os2, $os3) -contains $winver){
Write-Host "$setsystemtype without bitlocker"
Exit 1010
}

if ($setsystemtype -eq "desktop" -And $bitlockerkey -eq $null  -and ($os1, $os2, $os3) -contains $winver){
Write-Host "$setsystemtype without bitlocker"
Exit 0
}

if ($winver -eq ($os1, $os2, $os3) -contains $winver){
Write-Host "$bitlockerkey"
Exit 0
}
}

Answer 1

Let's see what this actually does:

if ($powershellversion -lt 4 -And $winver -eq $os1 -or $os2 -or $os3) { ... }

• If your powershell version is less than 4, and Win version is equal to os1, then proceed
• If os2 has a value, then proceed
• If os3 has a value, then proceed

The topic here is Operator Precedence, specifically, what happens first when evaluating a line of code, what happens second, third, and so on. Just like in algebra math, adding parens around part of the formula changes the order in whcih you read it.

So, you can mess around with parens to get your logic to work:

if($powershellversion -lt 4 -and ( ($winver -eq $os1) -or ($winver -eq $os2) -or ($winver -eq $os3) ))

In other words

• evaluate if PS version is < 4 ($powershellversion -lt 4), -and
• evaluate if winver is either os1, os2 or os3: ( ($winver -eq $os1) -or ($winver -eq $os2) -or ($winver -eq $os3) ).

Or, you can rearrange your logic a bit by putting your os variables into an array, and seeing if $winver is in there:

if($powershellversion -lt 4 -and $winver -in ($os1, $os2, $os3)) { ... }

Edit: Or

if($powershellversion -lt 4 -and ($os1, $os2, $os3) -contains $winver) { ... }

for backwards compatibility with v2.0.