using System.Diagnostics;
using System.IO;
using System.Threading;

class Program
{
    static void Main()
    {
        var process = new Process();
        process.StartInfo.UseShellExecute = false;

        process.StartInfo.FileName = "echo";
        process.StartInfo.Arguments = "Hello World!";
        process.StartInfo.RedirectStandardOutput = true;

        if (process.Start()) Thread.Sleep(2000);
        process.WaitForExit();

        var output = process.StandardOutput.ReadToEnd();
        File.WriteAllText("out", output);

        process.StartInfo.FileName = "cat";
        process.StartInfo.Arguments = "out";
        process.StartInfo.RedirectStandardOutput = false;

        if (process.Start()) Thread.Sleep(1000);
        process.WaitForExit();
    }
}