Synchronously reading stdout of a process

Question

I am executing an exe file which contains some c code from my c# winform but I get the complete output of the c code only after the complete execution of exe. I want the exe to relay its output to my winform synchronously (line by line in realtime).

    var proc = new Process
      {
          StartInfo = new ProcessStartInfo
          {
              FileName = "background.exe",
              Arguments = command,
              UseShellExecute = false,
              RedirectStandardOutput = true,
              CreateNoWindow = true
          }
      };


      proc.Start();
      while (!proc.StandardOutput.EndOfStream)
      {
          ConsoleWindow.AppendText(proc.StandardOutput.ReadLine());
          ConsoleWindow.AppendText(Environment.NewLine);

      }

What do you mean `some c code`? No text gets written to output unless the executing *process* put it there. You should check the code of `background.exe`. And make sure that `background.exe` is actually a compiled, binary executable file and not just a C file with a different extension — Panagiotis Kanavos, Mar 29 '16 at 11:45
Did you checked this [question](http://stackoverflow.com/questions/285760/how-to-spawn-a-process-and-capture-its-stdout-in-net) and this [question](http://stackoverflow.com/questions/18588659/redirect-process-output-c-sharp) ? — Dudi Keleti, Mar 29 '16 at 11:51
Checked all the code examples and they read the output only after the process is finished. — Dinesh wakti, Mar 29 '16 at 12:07

score 0 · Answer 1 · answered Mar 29 '16 at 13:29

Try this, which is loosely adapted from this example:

    private void button1_Click(object sender, EventArgs e)
    {
        var consoleProcess = new Process
        {
            StartInfo =
            {
                FileName =
                    @"background.exe",
                UseShellExecute = false,
                RedirectStandardOutput = true
            }
        };

        consoleProcess.OutputDataReceived += ConsoleOutputHandler;
        consoleProcess.StartInfo.RedirectStandardInput = true;
        consoleProcess.Start();
        consoleProcess.BeginOutputReadLine();
    }

    private void ConsoleOutputHandler(object sendingProcess,
        DataReceivedEventArgs outLine)
    {
        // This is the method in your form that's 
        // going to display the line of output from the console.
        WriteToOutput(outLine.Data);
    }

Note that the event handler that receives the output from the console is executing on a different thread, so you have to ensure that whatever you use to display the output on your form occurs on the UI thread.

No, not in the sense of async methods that return `Task`. It begins an async operation. But it is not an async method. — Scott Hannen, Jun 09 '22 at 14:17

Synchronously reading stdout of a process

1 Answers1