c# - How to asynchronously read the standard output stream and standard error stream at once

Question

I want to read the ouput of a process in the form as is in a console (standard output is blended with standard error in one stream). Is there a way how to do it?

I was thinking about using

ProcessStartInfo.UseShellExecute = true;  

but then I cannot read asynchronously the output. If I set

process.ProcessStartInfo.UseShellExecute = false;  
process.StartInfo.RedirectStandardOutput = true;
process.OutputDataReceived += new DataReceivedEventHandler(partialOutputHandler);

then I can read standard output (I can do the same for standard error) but I don't know how to simulate the behavior of console (the blending of stdout and stderr).

This is similar to Linux which has the feature of redirecting standard error stream to the standard output stream; how?

Answer 1

Do you mean something like this?

SynchronizationContext _syncContext;
MyForm()
{
    _syncContext = SynchronizationContext.Current;
}

void StartProcess()
{
    using (var process = new Process
        {
            StartInfo = new ProcessStartInfo
            {
                FileName = "myProcess.exe",
                UseShellExecute = false,
                RedirectStandardOutput = true,
                RedirectStandardError = true,
            }
        })
    {
        process.OutputDataReceived += (sender, args) => Display(args.Data);
        process.ErrorDataReceived += (sender, args) => Display(args.Data);

        process.Start();
        process.BeginOutputReadLine();
        process.BeginErrorReadLine();

        process.WaitForExit(); //you need this in order to flush the output buffer
    }   
}

void Display(string output)
{
    _syncContext.Post(_ => myTextBox.AppendText(output), null);
}