Execute powershell command from C#

Question

I trying to execute this powershell command from C#

gci C:\Ditectory -Recurse | unblock-file -whatif

using this code

        Runspace space = RunspaceFactory.CreateRunspace();
        space.Open();
        space.SessionStateProxy.Path.SetLocation(directoryPath);
        Pipeline pipeline = space.CreatePipeline();
        pipeline.Commands.Add("get-childitem");

        pipeline.Commands.Add("Unblock-File");
        pipeline.Commands.Add("-whatif");
        var cresult = pipeline.Invoke();
        space.Close();

I keep getting an exception about the whatif not being recognized command. Can I use whatif from C#

Mike Zboray · Accepted Answer · 2014-04-30 04:31:05Z

3

WhatIf is a parameter not a command, so it should be added to the Parameters collection of the command object for Unblock-File. However, this is made awkward by the API which returns void from Commands.Add. I suggest a using a small set of helper extension methods which will allow you to use a builder-like syntax:

internal static class CommandExtensions
{
    public static Command AddCommand(this Pipeline pipeline, string command)
    {
        var com = new Command(command);
        pipeline.Commands.Add(com);
        return com;
    }

    public static Command AddParameter(this Command command, string parameter)
    {
        command.Parameters.Add(new CommandParameter(parameter));
        return command;
    }

    public static Command AddParameter(this Command command, string parameter, object value)
    {
        command.Parameters.Add(new CommandParameter(parameter, value));
        return command;
    }
}

Then your code is simple:

pipeline.AddCommand("Get-ChildItem").AddParameter("Recurse");
pipeline.AddCommand("Unblock-File").AddParameter("WhatIf");
var results = pipeline.Invoke();
space.Close();

edited Apr 30, 2014 at 4:31

answered Apr 30, 2014 at 3:31

Mike Zboray

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3 Comments

user3373870 Over a year ago

Thanks for the extension methods, I have tried them and I still cannot see the result. I Modified the code to add the path to the Get-ChildItem but no dice Pipeline pipeline = space.CreatePipeline(); pipeline.AddCommand("Get-ChildItem").AddParameter("Path",dlg.SelectedPath).AddParameter("Recurse"); pipeline.AddCommand("Unblock-File").AddParameter("WhatIf"); pipeline.Commands.Add("Out-String"); var results = pipeline.Invoke();

Mike Zboray Over a year ago

@user3373870 It looks like the output of WhatIf does not go to the pipeline and is sent directly to the host. Therefore you need to implement your own PSHostUserInterface object. From what I can tell this is a non-trivial undertaking. Best to ask another question after you've done some research.

user3373870 Over a year ago

found out why the script was failing. Intelitrace is showing + Caught: "Unable to load DLL 'wldp.dll': The specified module could not be found. (Exception from HRESULT: 0x8007007E)" (System.DllNotFoundException)

Andy Arismendi · Accepted Answer · 2014-04-30 03:27:04Z

1

Whatif is a parameter, not a command. Try the AddParameter method instead:

http://msdn.microsoft.com/en-us/library/dd182433(v=vs.85).aspx

answered Apr 30, 2014 at 3:27

Andy Arismendi

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