如何从调用该 PowerShell 脚本的 C# 代码回答 Read-Host？

Question

I need to run PowerShell script from inside my C# code. That is easy. But then, my PowerShell script contains several Read-Host commands. Normally, the script execution would stop and the user should manually enter some value to PowerShell consoleas an answer. But what I need is to answer to these Read-Host requests from the same code in C# that executed and controls the flow of that script. In other words I need my script to stop at some point and await for some data input from my C# code, then get it and continue execution.

I found how to run PS from C#, I found how to pass arguments or initial variables from C# to PS script when launching it, but I can't find any way how to make my script await for some data from the host application, receive it and continue exectuion within host application, all these during runtime of script, not on its launch.

Can you please guide me to some direction fo search or code that might help?

Answer 1

You can call WriteLine() on the StandardInput of the process. That will provide data for one Read-Host in the script.

To do so make sure UseShellExecute of the respective ProcessStartInfo is set to false and its RedirectStandardInput to true .

So for example

    Process p = Process.Start(new ProcessStartInfo()
    {
        FileName = "powershell",
        Arguments = @"C:\Users\Konstantin\ps.ps1",
        UseShellExecute = false,
        RedirectStandardInput = true,
    });

    p.StandardInput.WriteLine("abc");

will provide "abc" to the first Read-Host of the script C:\\Users\\Konstantin\\ps.ps1 .

If there are more Read-Host s call WriteLine() again. Or you can use string concatenation with StandardInput.NewLine and just use Write . For example

p.StandardInput.Write("abc" + StandardInput.NewLine + "xyz" + StandardInput.NewLine);

will provide "abc" for the first and "xyz" for the second Read-Host .

Answer 2

If you're invoking the PowerShell script in-process then the only way to override the behavior of Read-Host is to define a custom PSHost for the process. The behavior is defined by the method PSHostUserInterface.ReadLine . Here is a bare minimum example of what you need to override just Read-Host .

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Globalization;
using System.Management.Automation;
using System.Management.Automation.Host;
using System.Management.Automation.Runspaces;
using System.Security;


namespace CustomHostExample
{
    public static class Program
    {
        public static void Main()
        {
            var host = new CustomPSHost();
            using (Runspace rs = RunspaceFactory.CreateRunspace(host))
            using (PowerShell pwsh = PowerShell.Create())
            {
                rs.Open();
                pwsh.Runspace = rs;
                pwsh.AddCommand("Read-Host").Invoke();
            }
        }
    }

    public class CustomPSHost : PSHost
    {
        public override string Name => "Custom Host";

        public override Version Version => new Version(1, 0, 0, 0);

        public override Guid InstanceId { get; } = Guid.NewGuid();

        public override PSHostUserInterface UI { get; } = new CustomPSHostUserInterface();

        public override CultureInfo CurrentCulture => CultureInfo.CurrentCulture;

        public override CultureInfo CurrentUICulture => CultureInfo.CurrentUICulture;

        public override void EnterNestedPrompt()
            => throw new NotImplementedException();

        public override void ExitNestedPrompt()
            => throw new NotImplementedException();

        public override void NotifyBeginApplication()
            => throw new NotImplementedException();

        public override void NotifyEndApplication()
            => throw new NotImplementedException();

        public override void SetShouldExit(int exitCode)
            => throw new NotImplementedException();
    }

    public class CustomPSHostUserInterface : PSHostUserInterface
    {
        public override PSHostRawUserInterface RawUI { get; } = new CustomPSHostRawUserInterface();

        public override string ReadLine()
        {
            return Console.ReadLine();
        }

        public override Dictionary<string, PSObject> Prompt(
            string caption,
            string message,
            Collection<FieldDescription> descriptions)
            => throw new NotImplementedException();

        public override int PromptForChoice(
            string caption,
            string message,
            Collection<ChoiceDescription> choices,
            int defaultChoice)
            => throw new NotImplementedException();

        public override PSCredential PromptForCredential(
            string caption,
            string message,
            string userName,
            string targetName,
            PSCredentialTypes allowedCredentialTypes,
            PSCredentialUIOptions options)
            => throw new NotImplementedException();

        public override PSCredential PromptForCredential(
            string caption,
            string message,
            string userName,
            string targetName)
            => throw new NotImplementedException();

        public override SecureString ReadLineAsSecureString()
            => throw new NotImplementedException();

        public override void Write(ConsoleColor foregroundColor, ConsoleColor backgroundColor, string value)
            => throw new NotImplementedException();

        public override void Write(string value)
            => throw new NotImplementedException();

        public override void WriteDebugLine(string message)
            => throw new NotImplementedException();

        public override void WriteErrorLine(string value)
            => throw new NotImplementedException();

        public override void WriteLine(string value)
            => throw new NotImplementedException();

        public override void WriteProgress(long sourceId, ProgressRecord record)
            => throw new NotImplementedException();

        public override void WriteVerboseLine(string message)
            => throw new NotImplementedException();

        public override void WriteWarningLine(string message)
            => throw new NotImplementedException();
    }

    public class CustomPSHostRawUserInterface : PSHostRawUserInterface
    {
        public override ConsoleColor BackgroundColor
        {
            get => throw new NotImplementedException();
            set => throw new NotImplementedException();
        }

        public override Size BufferSize
        {
            get => throw new NotImplementedException();
            set => throw new NotImplementedException();
        }

        public override Coordinates CursorPosition
        {
            get => throw new NotImplementedException();
            set => throw new NotImplementedException();
        }

        public override int CursorSize
        {
            get => throw new NotImplementedException();
            set => throw new NotImplementedException();
        }

        public override ConsoleColor ForegroundColor
        {
            get => throw new NotImplementedException();
            set => throw new NotImplementedException();
        }

        public override Coordinates WindowPosition
        {
            get => throw new NotImplementedException();
            set => throw new NotImplementedException();
        }

        public override Size WindowSize
        {
            get => throw new NotImplementedException();
            set => throw new NotImplementedException();
        }

        public override string WindowTitle
        {
            get => throw new NotImplementedException();
            set => throw new NotImplementedException();
        }

        public override bool KeyAvailable
            => throw new NotImplementedException();

        public override Size MaxPhysicalWindowSize
            => throw new NotImplementedException();

        public override Size MaxWindowSize
            => throw new NotImplementedException();

        public override void FlushInputBuffer()
            => throw new NotImplementedException();

        public override BufferCell[,] GetBufferContents(Rectangle rectangle)
            => throw new NotImplementedException();

        public override KeyInfo ReadKey(ReadKeyOptions options)
            => throw new NotImplementedException();

        public override void ScrollBufferContents(
            Rectangle source,
            Coordinates destination,
            Rectangle clip,
            BufferCell fill)
            => throw new NotImplementedException();

        public override void SetBufferContents(Coordinates origin, BufferCell[,] contents)
            => throw new NotImplementedException();

        public override void SetBufferContents(Rectangle rectangle, BufferCell fill)
            => throw new NotImplementedException();
    }
}

Note: Every method shown that doesn't throw a NotImplementedException must be implemented or PowerShell will deadlock or throw. More methods will need to be implemented depending on what else of PSHost is called.