Execute multiple command lines with output

I assume that you are actually asking about how to catch outputs from all the commands you want to have executed in the (one) process.

Here is a version of a solution I came up with a long time ago, when I was a rookie here..

The trick is to collect the output as is comes along by listening to events the Process will trigger whenever output gets created: OutputDataReceived and ErrorDataReceived. We need to run things async for this to work, so it will look a little more complicated than the usual examples, which only have one process executing one command..:

First a few variables:

    Queue<string> cmdQueue = new Queue<string>();
    static StringBuilder StdOutput = new StringBuilder();
    static StringBuilder ErrOutput = new StringBuilder();

    Process p = null;
    Task processTask = null;
    bool processIsRunning = false;

Here is a button click event that starts processing all commands from a multiline TextBox. Output gets collected in the two StringBuilders; when the queue is empty, I wait a little longer..:

private void button1_Click(object sender, EventArgs e)
{
    cmdQueue = new Queue<string>(tb_commands.Lines.ToList());

    setupProcess();
    startProcessTask();

    while (cmdQueue.Count > 0) Thread.Sleep(100);
    Thread.Sleep(500);
    tb_out.AppendText(StdOutput + "\r\n" + ErrOutput + "\r\n");
}

Here is the routine that set up the Process. Here we register two events that will notify us when there are lines in the output streams..:

private void setupProcess()
{
    p = new Process();
    ProcessStartInfo info = new ProcessStartInfo();
    info.FileName = "cmd.exe";
    info.CreateNoWindow = true;
    info.RedirectStandardOutput = true;
    info.RedirectStandardError = true;
    info.RedirectStandardInput = true;
    info.UseShellExecute = false;

    p.OutputDataReceived += new DataReceivedEventHandler(OutputDataHandler);
    p.ErrorDataReceived += new DataReceivedEventHandler(ErrorDataHandler);
    StdOutput = new StringBuilder();
    ErrOutput = new StringBuilder();
    p.StartInfo = info;
}

After the setup we can start a Task that will start our Process asynchonously..:

private void startProcessTask()
{
    var task = Task.Factory.StartNew(() => startProcess());
    processTask = task;
}

..and finally here is the async method that after starting the Process and beginning with the asynchronous read operations on the redirected streams, keeps feeding it all lines from the command queue.

private async void startProcess()
{
    try { p.Start(); processIsRunning = true; } catch
    {
        ErrOutput.Append("\r\nError starting cmd process.");
        processIsRunning = false;
    }

    p.BeginOutputReadLine();
    p.BeginErrorReadLine();

    using (StreamWriter sw = p.StandardInput)
    {

        if (sw.BaseStream.CanWrite)
            do
            {
                try
                {
                    string cmd = cmdQueue.Dequeue();
                    if (cmd != null & cmd != "") await sw.WriteLineAsync(cmd);
                } catch { }
            } while (processIsRunning);
        try { p.WaitForExit(); } catch { ErrOutput.Append("WaitForExit Error.\r\n"); }
    }
}

The last pieces are the two events we have registered for reading the output from the two streams and adding them to the StringBuilders:

private static void OutputDataHandler(object sendingProcess, DataReceivedEventArgs outLine)
{
    if (!String.IsNullOrEmpty(outLine.Data))
    {  
        StdOutput.Append(Environment.NewLine + outLine.Data);
    }
}

private static void ErrorDataHandler(object sendingProcess, DataReceivedEventArgs outLine)
{
    if (!String.IsNullOrEmpty(outLine.Data))
    {  
        ErrOutput.Append(Environment.NewLine + outLine.Data);
    }
}

Note that this works fine for all sorts of commands you can feed into the process, including FTP. Here I change my codepage, show the images I have before, log in to an FTP server, call up the help page, cd and dir, download an image, close the connection and check the images I have now..:

One Caveat: There must be something wrong in the way I wrote this, as VS keeps complaining about a System.InvalidOperationException and the exe file hogs ~10% cpu. Helping me out would be very much appreciated..