Capturing process output via OutputDataReceived event

Boris picture Boris · Jul 24, 2012 · Viewed 33.6k times · Source

I'm trying to capture process output in "realtime" (while it's running). The code I use is rather simple (see below). For some strange reason the OutputDataReceived event is never called. Why?

private void button2_Click(object sender, EventArgs e)
    {
      // Setup the process start info
      var processStartInfo = new ProcessStartInfo("ping.exe", "-t -n 3 192.168.100.1")
      {
        UseShellExecute = false,
        RedirectStandardOutput = true
      };

      // Setup the process
      mProcess = new Process { StartInfo = processStartInfo, EnableRaisingEvents = true };

      // Register event
      mProcess.OutputDataReceived += OnOutputDataReceived;

      // Start process
      mProcess.Start();
      mProcess.WaitForExit();
    }

    void OnOutputDataReceived(object sender, DataReceivedEventArgs e)
    {
       //Never gets called...
    }

Answer

Chris picture Chris · Jul 24, 2012

You need to call

mProcess.BeginOutputReadLine();

BeginOutputReadLine - "Begins asynchronous read operations on the redirected StandardOutput stream of the application."