Question

I am working with a winform that runs a cmd in the background, redirecting input and output asynchronously.

Currently, the winform iterating through an array of commands, writing each to the cmd via the StreamWriter the StandardInput is redirected to. How can I force the loop to wait until the present command is complete in the cmd before writing the next line in?

EDIT: I took out all of my actual project code, and replaced it with this, a stripped down version of what I’m trying to do, only including components of my project relevant to my question.

public partial class Form1 : Form
{

    public delegate void WriteToConsoleMethod(string text);
    Process _process;

    string[] _commands = 
    {
        "echo hello world",
        "echo my name is T.K.",
        "echo Here is a list of commands"
    };
    public Form1()
    {
        InitializeComponent();
        ProcessStartInfo processStartInfo = new ProcessStartInfo("cmd")
        {
            RedirectStandardError = true,
            RedirectStandardInput = true,
            RedirectStandardOutput = true,
            UseShellExecute = false,
            CreateNoWindow = true
        };

        _process = Process.Start(processStartInfo);
        _process.OutputDataReceived += new DataReceivedEventHandler(new DataReceivedEventHandler(DataReceived_EventHandler));
        _process.ErrorDataReceived += new DataReceivedEventHandler(new DataReceivedEventHandler(DataReceived_EventHandler));
        _process.BeginErrorReadLine();
        _process.BeginOutputReadLine();
    }

    private void DataReceived_EventHandler(object sender, DataReceivedEventArgs e)
    {
        IAsyncResult result = this.BeginInvoke(new WriteToConsoleMethod(writeToConsole), new object[] { e.Data + Environment.NewLine });
        this.EndInvoke(result);
    }

    private void writeToConsole(string output)
    {
        txtbxConsole.AppendText(output);
    }

    private void btnBegin_Click(object sender, EventArgs e)
    {
        foreach (string command in _commands)
        {
            _process.StandardInput.WriteLine(command);
            // I want a way to pause here until the cmd has finished processing the command.
        }
    }
}

Answer 1

I don’t think there is anything built-in that will support that. However you could send your own special command and then wait until you see this in the output for example ,
something like :

    const string Separator= "---Command Completed--\xE3\xE2\xE1\xE0\xE3";   
    // Has to be something that won't occur in normal output.  

    volatile bool finished = false;

    private void button1_Click(object sender, EventArgs e)
    {         
        foreach (string command in _commands)
            Run(command);
    }

    private void writeToConsole(string output)
    {
        if (output.IndexOf(Separator) >= 0)
            finished = true;
        else
            richTextBox1.AppendText(output);
    }


    private void Run(string command)
    {
        finished = false;
        _process.StandardInput.WriteLine(command);
        _process.StandardInput.WriteLine("@echo " + Seperator);
        while (!finished)
        {
            Application.DoEvents();
            System.Threading.Thread.Sleep(100);
        }
    }

    private void Form1_FormClosing(object sender, FormClosingEventArgs e)
    {
        finished = true;
    }