Powershell: OS Detection

What OS am I executing on? What bitness? Some Handy Functions to Use

Sometimes, it's important to know what OS you are running on, and/or how many bits that OS has. Here are some useful functions which can be reused in other Powershell scripts (a future post may include putting such things into a Powershell Module). Please note that this hasn't been 100% tested on all of the OSes identified, but should work*.

The other two functions are about detecting bitness - Get-OSBitness() will tell you if you are on a 64-bit or 32-bit OS, and Get-CurrentProcessBitness() will tell you what the current Powershell execution-engine is (ie you can detect if you are running on the 32-bit powershell.exe on a 64-bit OS). I can't really image G-CPB() being used much, but here it is anyway.

* Please also note that the Win8.1/2012R2 detection is known to be sometimes incorrect, and these OSes can instead show up as Win8/2012 (respectively); this is because Microsoft broke the detection mechanism in these OSes, and each application now must use a manifest.xml file to flag itself as a Win8.1/2012R2 app (as ooposed to a legacy <= Win8) - I'm pretty sure Powershell.exe is properly manifested and should detect as Win8.1, but the default Powershell ISE is not (at this current time) and will show Win8.



Function Get-OSVersion() {
    # Version numbers as per http://www.gaijin.at/en/lstwinver.php
    $osVersion = "Version not listed"
    $os = (Get-WmiObject -class Win32_OperatingSystem)
    Switch (($os.Version).Substring(0,3)) {
        "5.1" { $osVersion = "XP" }
        "5.2" { $osVersion = "2003" }
        "6.0" { If ($os.ProductType -eq 1) { $osVersion = "Vista" } Else { $osVersion = "2008" } }
        "6.1" { If ($os.ProductType -eq 1) { $osVersion = "7" } Else { $osVersion = "2008R2" } }
        "6.2" { If ($os.ProductType -eq 1) { $osVersion = "8" } Else { $osVersion = "2012" } }
        # 8.1/2012R2 version detection can be broken, and show up as "6.2", as per http://www.sapien.com/blog/2014/04/02/microsoft-windows-8-1-breaks-version-api/
        "6.3" { If ($os.ProductType -eq 1) { $osVersion = "8.1" } Else { $osVersion = "2012R2" } }
    }
    return $osVersion
}


Function Get-CurrentProcessBitness() {
    # This function finds the bitness of the powershell.exe process itself (ie can detect 32-bit powershell.exe on a win64)
    $thisProcessBitness = 0
    switch ([IntPtr]::Size) {
        "4" { $thisProcessBitness = 32 }
        "8" { $thisProcessBitness = 64 }
    }
    return $thisProcessBitness
}

Function Get-OSBitness() {
    # This function finds the bitness of the OS itself (ie will detect 64-bit even if you're somehow using 32-bit powershell.exe)
    $OSBitness = 0
    switch ((Get-WmiObject Win32_OperatingSystem).OSArchitecture) {
        "32-bit" { $OSBitness = 32 }
        "64-bit" { $OSBitness = 64 }
    }
    return $OSBitness
}