Create new PowerShell process with pipes

Question

Running this from CMD produces the correct result:

powershell -command "& Get-DiskImage -imagepath C:\\file.vhdx | Get-Disk"
<Here is some stuff regarding VHD>

I want to achieve exactly the same running this from C# (there's no way to run it directly, use some PowerShell related .NET stuff, or something else).

My code is the following:

static void LaunchCommandLineApp()
{
    ProcessStartInfo startInfo = new ProcessStartInfo();
    startInfo.CreateNoWindow = false;
    startInfo.UseShellExecute = false;
    startInfo.FileName = "powershell";
    startInfo.WindowStyle = ProcessWindowStyle.Hidden;
    startInfo.RedirectStandardOutput = true;
    startInfo.Arguments = "-command \" & get-diskimage -imagepath C:\\file.vhdx | Get-Disk \"";

    using (Process exeProcess = Process.Start(startInfo)) {
        exeProcess.WaitForExit();
        var out = exeProcess.StandardOutput.ReadToEnd();
    }
}

And in "out" I am getting an error:

Get-Disk : Cannot validate argument on parameter 'Number'. The argument is null. Provide a valid value for the argument, and then try running the command again.

But exactly the same code works in CMD. If I remove "| Get-Disk" from arguments, I will get correct output in "out" from the Get-DiskImage cmdlet.

Also, I have tried to play with curly braces, as other answers suggested - error haven't changed.

What shall I put in "startInfo.Arguments", so my output of "Get-DiskImage" will be correctly piped to the next cmdlet?

What is the output from get-diskimage? The input is looking for the wrong type. — Clayton Harbich, Apr 01 '19 at 17:13
@ClaytonHarbich just a text with information, if we omit "| Get-Disk" — Starl1ght, Apr 01 '19 at 17:16
Possible duplicate of [C# Process Start needs Arguments with double quotes - they disappear](https://stackoverflow.com/questions/14339701/c-sharp-process-start-needs-arguments-with-double-quotes-they-disappear) — , Apr 01 '19 at 17:39
That's a good point. Does the command work in a PowerShell terminal? — Clayton Harbich, Apr 01 '19 at 19:12

score 1 · Accepted Answer · edited Jul 15 '19 at 22:16

1

This is not actually a problem with the difference between running from the command line and from C#. I created a test VHDX and got the same (error) result whether run from C# or the command line, as shown by the OP.

In both cases, omitting the | Get-Disk part showed information about the disk image, which lacked a disk number, which is exactly what Get-Disk was complaining about. I suspect the image needs to be mounted for it to have a disk number.

edited Jul 15 '19 at 22:16

Peter Mortensen

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answered Apr 01 '19 at 20:58

jazzdelightsme

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While my image have mounted - for some reason C# (even plain C system() call) both omitting number. So, C# is not guilty. – Starl1ght Apr 02 '19 at 07:38

Create new PowerShell process with pipes

1 Answers1