Comments on: A guide to PowerShell’s Advanced Functions

By: Stuart Henderson

Stuart Henderson — Tue, 10 Mar 2009 20:47:25 +0000

Hi Jaykul,

I think it was I who posted the message in the NG asking for clarification.

As usual you come through with something far exceeding what I could have hoped for. I can’t thank you enough for the help you have provided me both in the NG and the IRC.

I’m gonna email Jeffrey Snover every week till he gives you the MVP and backdates it a year Haha!!

Thanks again,
Stuart

By: Joel 'Jaykul' Bennett

Joel 'Jaykul' Bennett — Wed, 04 Mar 2009 13:57:52 +0000

Yeah, that’s probably because $PWD -ne [Environment]::CurrentDirectory

If you want it to be, you should add a line to your prompt function to set it: [Environment]::CurrentDirectory = $pwd

By: Klaus Schulte

Klaus Schulte — Wed, 04 Mar 2009 07:39:27 +0000

Hello Joel,

thank you very much for your reply!
I won’t argue any more … but I’d like to add these lines and finish the discussion anyway. Things are sometimes not the way they should be and I can live with that

# A credential object: $c was created
PSH:\Powershell>$c
UserName                 Password

DOMS\schulte            System.Security.SecureString
# My CurrentDirectory is writeable (and readable) by my account

PS H:\Powershell> out-file -inp "I can write to $([Environment]::CurrentDirectory)!" "$([Environment]::CurrentDirectory)\WriteToMe.txt"
# I CAN'T start a process with my Credentials:

PS H:\Powershell> [System.Diagnostics.Process]::Start("Notepad", $c.GetNetworkCredential().UserName, $c.Password, $c.GetNetworkCredential().Domain)
Exception calling "Start" with "4" argument(s): "Der Verzeichnisname ist ung�ltig"

At line:1 char:36

+ [System.Diagnostics.Process]::Start &lt;&lt;&lt; [System.Diagnostics.Process]::Start("Notepad")
Handles  NPM(K)    PM(K)      WS(K) VM(M)   CPU(s)     Id ProcessName                                                             

-------  ------    -----      ----- -----   ------     -- -----------                                                             

      0       0      140         84     1     0,02   4304 notepad                                                                 

 

Life is NOT ALWAYS dair ******

kind regards, Klaus

By: Joel 'Jaykul' Bennett

Joel 'Jaykul' Bennett — Tue, 03 Mar 2009 22:19:56 +0000

Klaus: I haven’t seen that invalid working directory exception … you must be trying to start the process with an account that doesn’t have rights to the folder you’re in.

When you launch an app without specifying the Working Directory, it will be set to [Environment]::CurrentDirectory … if you use an account that can’t access that folder, you will get a Win32Exception “The directory name is invalid” (in English). The simplest solution is to set your CurrentDirectory, but as you discovered, it also works to use the ProcessStartInfo — which holds many other powers too

By: Joel 'Jaykul' Bennett

Joel 'Jaykul' Bennett — Tue, 03 Mar 2009 21:51:16 +0000

chad: good catch

By: Chad Miller

Chad Miller — Tue, 03 Mar 2009 17:36:38 +0000

Modules and Advanced functions seem a lot clearer to me now —Thanks for the guide.

I’ve also heard the term “library” used to describe function(s) which you source. Should “processutility.ps1” be “processutility.psm1” in 4a?

By: Jason Archer

Jason Archer — Tue, 03 Mar 2009 17:35:53 +0000

Thank you for writing this up, it was sorely needed.

By: David Mohundro

David Mohundro — Tue, 03 Mar 2009 14:15:26 +0000

Apparently I don’t even know my openid URL. Sorry about messing up that last comment.

By: David Mohundro

David Mohundro — Tue, 03 Mar 2009 14:09:33 +0000

Nice guide – thanks for posting it! I really haven’t been taking advantage of what’s possible with advanced functions. So far, I’ve primarily been using it to require parameters (with [Parameter(Mandatory=$true)]). I need to try some more features out.

By: Klaus Schulte

Klaus Schulte — Tue, 03 Mar 2009 13:18:34 +0000

Dear Joel,

firstOfAll: thank you very much for your powershell guides!!!
I love to read through them … (if I’ve got the time) ...

Just one question and a short comment:

1) You specified: DefaultParameterSetName=“NoCreds”
I’m no PS-expert … but shouldn’t there be a ParameterSet with the tag “NoCred” defined somewhere in the param-section?

2) If I try to start a process with:

[Diagnostics.Process]::Start("notepad.exe", $c.GetNetworkCredential().UserName, $c.Password, $c.GetNetworkCredential().Domain)

... that’s what your adv.function will issue, if I add a parameter ( $c = get-Credential ) to the call:
“Start-Process “notepad.exe” -Credential $c”
I’m receiving an exception

PS C:\Dokumente und Einstellungen\Schulte> Start-Process “notepad.exe” -Credential $c
Exception calling “Start” with “4” argument(s): “Der Verzeichnisname ist ung�ltig”
At H:\Powershell\Start-Process.ps1:38 char:35
+ [Diagnostics.Process]::Start <<<< (
+ CategoryInfo : NotSpecified: (:) [], MethodInvocationException
+ FullyQualifiedErrorId : DotNetMethodException

That exception ( in english: “invalid directory name” ) occurs only, if I add the Credentials to the call. This works:
Start-Process “notepad.exe”

As I figured out, that’s a problem with the “working directory”, that you can set explicitly using the “StartProcessInfo” parameter as an overload to the Start method. Using C# this works:

System.Diagnostics.ProcessStartInfo psi = new System.Diagnostics.ProcessStartInfo();

psi.Arguments = null;

psi.Domain = "MyDomain";

psi.FileName = @"c:\windows\System32\Notepad.exe";

psi.Password = pwd;

psi.UserName = "UserName";

psi.UseShellExecute = false;

psi.WorkingDirectory="C:\";

System.Diagnostics.Process.Start(psi);

Commenting out the psi.WorkingDirectory line results in the “invalid directory” exception!

Strange but true

king regards, Klaus