Why does Test-Path cmdlet incorrectly report false when I use an environment variable?

Question

I'm on a Win 7 machine using Powershell 4.0

PS C:\> $psversiontable

Name                           Value                                                                                                                                                               
----                           -----                                                                                                                                                               
PSVersion                      4.0                                                                                                                                                                 
WSManStackVersion              3.0                                                                                                                                                                 
SerializationVersion           1.1.0.1                                                                                                                                                             
CLRVersion                     4.0.30319.42000                                                                                                                                                     
BuildVersion                   6.3.9600.18728                                                                                                                                                      
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0}                                                                                                                                                
PSRemotingProtocolVersion      2.2 

See command line exercise below. The dll exists. The environment variable exists and has the correct path. When I use the the environment variable with Test-Path, it incorrectly reports $false. When I use a string literal with Test-Path, it correctly reports $true

Why does Test-Path incorrectly report false when I use the environment variable?

PS C:\> dir "C:\Program Files (x86)\Gemalto\NET Smartcard Framework SDK\v2.3.0\bin\SmartCard.Runtime.dll"

    Directory: C:\Program Files (x86)\Gemalto\NET Smartcard Framework SDK\v2.3.0\bin

Mode                LastWriteTime     Length Name                                                                                                                                                  
----                -------------     ------ ----                                                                                                                                                  
-a---         1/13/2012   6:57 PM     131072 SmartCard.Runtime.dll                                                                                                                                 

PS C:\> Write-Host $env:GEMALTO_SMARTCARD_DLL
"C:\Program Files (x86)\Gemalto\NET Smartcard Framework SDK\v2.3.0\bin\SmartCard.Runtime.dll"

PS C:\> Test-Path $env:GEMALTO_SMARTCARD_DLL

False

PS C:\> Test-Path "C:\Program Files (x86)\Gemalto\NET Smartcard Framework SDK\v2.3.0\bin\SmartCard.Runtime.dll"
True    

Answer 1

As you print Write-Host $env:GEMALTO_SMARTCARD_DLL, then you can see that environment variable GEMALTO_SMARTCARD_DLL includes literal " as part of its value. That is incorrect. You should remove them before passing to Test-Path: $env:GEMALTO_SMARTCARD_DLL.Trim('"'), for example.

Note: although " is invalid character for file system path, it is not invalid character for PowerShell path, as it is not limited for file system only.

New-PSDrive -Name '"C' -PSProvider Variable -Root \
${Program Files (x86)\Gemalto\NET Smartcard Framework SDK\v2.3.0\bin\SmartCard.Runtime.dll"} = 'Value'
Test-Path $env:GEMALTO_SMARTCARD_DLL

Answer 2

Your problem is not due to environment variables (they are just variables in a different drive- Env: versus Variable:), but with the contents of your environment variable. If you are creating this variable in cmd, you should use the following syntax:

SET "GEMALTO_SMARTCARD_DLL=C:\Program Files(x86)\.."

Arguments in PowerShell are a bit smarter than batch arguments and passing a variable counts as an argument in its entirety, regardless of its contents.

In your specific case, your variable has quote characters as part of the contents which doesn't make sense to Test-Path:

PS C:\> $Env:GEMALTO_SMARTCARD_DLL
"C:\Program Files (x86)\Gemalto\NET Smartcard Framework SDK\v2.3.0\bin\SmartCard.Runtime.dll"

You can fix this by fixing the declaration of the environment variable, or you can fix it in your code:

$GEMALTO_SMARTCARD_DLL = $Env:GEMALTO_SMARTCARD_DLL -replace '^"' -replace '"$'