C# Fremdes Programm starten + Eingaben senden + verarbeiten während es läuft.

using System;
    using System.Diagnostics;
    using System.IO;
     
    class Program {
        static void Main() {
            ProcessStartInfo start = new ProcessStartInfo();
            start.FileName = @"C:\MeinProgram.exe";
            start.UseShellExecute = false;
            start.RedirectStandardOutput = true;
            using (Process process = Process.Start(start)) {
                // Lesen allen Text from Process und gib ihn in der Console aus (als Beispiel)
                using (StreamReader reader = process.StandardOutput) {
                    string result = reader.ReadToEnd();
                    Console.Write(result);
                }
            }
        }
    }

BackgroundWorker worker;

private void Form1_Load(object sender, EventArgs e)
        {
            worker = new BackgroundWorker();
            worker.WorkerReportsProgress = true;
            worker.WorkerSupportsCancellation = true;

            worker.DoWork += new DoWorkEventHandler(worker_DoWork);
            worker.ProgressChanged +=
                        new ProgressChangedEventHandler(worker_ProgressChanged);
            worker.RunWorkerCompleted +=
                       new RunWorkerCompletedEventHandler(worker_RunWorkerCompleted);
        }

 void worker_DoWork(object sender, DoWorkEventArgs e)
        {
            Process proc = new Process();
            proc.EnableRaisingEvents = false;
            proc.StartInfo.FileName = "Pfad";
            proc.StartInfo.Arguments = "Arguments";
            proc.StartInfo.UseShellExecute = false;
            proc.StartInfo.CreateNoWindow = true;
            proc.StartInfo.WindowStyle = ProcessWindowStyle.Hidden;
            proc.StartInfo.RedirectStandardOutput = true; 
            proc.StartInfo.RedirectStandardInput = true;
            proc.Start();
            while (!proc.StandardOutput.EndOfStream)
            {
                worker.ReportProgress(0, proc.StandardOutput.ReadLine());
                // Zu 1. könntest du sowas in der Art nutzen
                if (Eingabe == true)
                        proc.StandardInput.Write("s");
            }
            proc.WaitForExit();
            proc.Close();
        }

void worker_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            // Zeile für Zeile vom StandardOutput
            string result = (e.UserState.ToString());            
        }

void worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {

        }

worker.RunWorkerAsync();