C#•2y ago

✅ Capturing process output

https://learn.microsoft.com/en-us/dotnet/api/system.diagnostics.process.outputdatareceived?view=net-7.0#examples I am using the following example to try and capture a process output and print it to a textbox at runtime. The process output is captured, but it is only printed after the process has terminated. how do I make sure to print at runtime?

  var path = "C:\\program.exe";
  Process process = new Process();
            process.StartInfo.FileName = path;
            process.StartInfo.UseShellExecute = false;
            process.StartInfo.RedirectStandardOutput = true;
            process.OutputDataReceived += new DataReceivedEventHandler((sender, e) =>
            {
                if (!String.IsNullOrEmpty(e.Data))
                {
                    output.Append(e.Data + "\r\n");
                }
            });
            process.Start();
            process.BeginOutputReadLine();
            process.WaitForExit();
            tboxConsole.AppendText(output.ToString());
            process.WaitForExit();
            process.Close();

  var path = "C:\\program.exe";
  Process process = new Process();
            process.StartInfo.FileName = path;
            process.StartInfo.UseShellExecute = false;
            process.StartInfo.RedirectStandardOutput = true;
            process.OutputDataReceived += new DataReceivedEventHandler((sender, e) =>
            {
                if (!String.IsNullOrEmpty(e.Data))
                {
                    output.Append(e.Data + "\r\n");
                }
            });
            process.Start();
            process.BeginOutputReadLine();
            process.WaitForExit();
            tboxConsole.AppendText(output.ToString());
            process.WaitForExit();
            process.Close();

Process.OutputDataReceived Event (System.Diagnostics)

Occurs each time an application writes a line to its redirected StandardOutput stream.

45 Replies

ero•2y ago

process.WaitForExit() does what it says

madogumglyniumOP•2y ago

what is that suppose to mean? i just tried not waiting for exit and i get no output at all

ero•2y ago

well sure you have to have both running kind of in parallel if you wait for the other process to exit, then your code will never read tboxConsole.AppendText before the process has exited but if you don't wait, then your code will reach tboxConsole.AppendText before any output has occurred

madogumglyniumOP•2y ago

i also tried capturing the process on a separate thread, but no luck. what would you suggest?

ero•2y ago

i would probably just change the textbox contents in the DataReceivedEventHandler

madogumglyniumOP•2y ago

lol i tried that too

ero•2y ago

and?

madogumglyniumOP•2y ago

no out put at all not even when the process has terminated is this what you mean?

process.OutputDataReceived += new DataReceivedEventHandler((sender, e) =>
{
    if (!String.IsNullOrEmpty(e.Data))
    {
        // Use BeginInvoke to update the UI in the main thread
        tboxConsole.BeginInvoke(new Action(() =>
        {
            tboxConsole.AppendText(e.Data + "\r\n");
        }));
    }
});

process.OutputDataReceived += new DataReceivedEventHandler((sender, e) =>
{
    if (!String.IsNullOrEmpty(e.Data))
    {
        // Use BeginInvoke to update the UI in the main thread
        tboxConsole.BeginInvoke(new Action(() =>
        {
            tboxConsole.AppendText(e.Data + "\r\n");
        }));
    }
});

ero•2y ago

something like that yeah

madogumglyniumOP•2y ago

well that didnt work unfortunatly :C

ZacharyPatten•2y ago

what kind of applicationis this? winforms?

ZacharyPatten•2y ago

if this is winforms, you probably need to call Refresh on the control to update it with the output: https://learn.microsoft.com/en-us/dotnet/api/system.windows.forms.control.refresh?view=windowsdesktop-7.0

Control.Refresh Method (System.Windows.Forms)

Forces the control to invalidate its client area and immediately redraw itself and any child controls.

ZacharyPatten•2y ago

but you should also be multithreading this for example, try adding

DataReceivedEventHandler((sender, e) =>
{
    if (!String.IsNullOrEmpty(e.Data))
    {
        output.Append(e.Data + "\r\n");
        this.Refresh(); // <- added this line
    }
});

DataReceivedEventHandler((sender, e) =>
{
    if (!String.IsNullOrEmpty(e.Data))
    {
        output.Append(e.Data + "\r\n");
        this.Refresh(); // <- added this line
    }
});

madogumglyniumOP•2y ago

i tried having the refresh run on a separate thread but no luck..

madogumglyniumOP•2y ago

this is what i tried:

 if (!String.IsNullOrEmpty(e.Data))
                {
                    output.Append(e.Data + "\r\n");
                    this.BeginInvoke(new Action(() =>
                    {
                        tboxConsole.AppendText(output.ToString());
                        this.Refresh();
                    }));
                }

 if (!String.IsNullOrEmpty(e.Data))
                {
                    output.Append(e.Data + "\r\n");
                    this.BeginInvoke(new Action(() =>
                    {
                        tboxConsole.AppendText(output.ToString());
                        this.Refresh();
                    }));
                }

ZacharyPatten•2y ago

it sounds like it should be working then based on your comments. I don't think I can help without being able to replicate your issue. If you can share your code so we can test it for ourselves please do

madogumglyniumOP•2y ago

I am pushing to github atm, https://github.com/karim-daman/Replication_Test.git really appretiate your attempt to help. NOTE: adjust the exe path so that the form can reference it.

GitHub

GitHub - karim-daman/Replication_Test

Contribute to karim-daman/Replication_Test development by creating an account on GitHub.

ero•2y ago

you gotta be trippin if you think anyone's just gonna launch this exe

madogumglyniumOP•2y ago

ur not suppose to be launching it lol i mean u can but the form would launch it when i hit start it's a published .netcore web api as an exe you can use a vm if ur sus

ero•2y ago

i mean you have to start it to do your replication

madogumglyniumOP•2y ago

no u dont u run the form, then click start, and the form would run the exe as a separate process

ero•2y ago

...which runs the exe which is what i'm saying

madogumglyniumOP•2y ago

i was clear about this since day one lol

ero•2y ago

anyway it works fine

madogumglyniumOP•2y ago

what? u see output? at run time?

ero•2y ago

yeah

madogumglyniumOP•2y ago

wtf no way

ero•2y ago

well no, i made changes

madogumglyniumOP•2y ago

show me!

ero•2y ago

cause your code still didn't make sense

using Process process = new()
{
    StartInfo = new()
    {
        FileName = /* */,
        UseShellExecute = false,
        RedirectStandardOutput = true,
        CreateNoWindow = true
    }
};

process.OutputDataReceived += new DataReceivedEventHandler((sender, e) =>
{
    if (string.IsNullOrEmpty(e.Data))
        return;

    BeginInvoke(() =>
    {
        tboxConsole.AppendText(e.Data + Environment.NewLine);
        tboxConsole.Refresh();
    });
});

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

using Process process = new()
{
    StartInfo = new()
    {
        FileName = /* */,
        UseShellExecute = false,
        RedirectStandardOutput = true,
        CreateNoWindow = true
    }
};

process.OutputDataReceived += new DataReceivedEventHandler((sender, e) =>
{
    if (string.IsNullOrEmpty(e.Data))
        return;

    BeginInvoke(() =>
    {
        tboxConsole.AppendText(e.Data + Environment.NewLine);
        tboxConsole.Refresh();
    });
});

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

madogumglyniumOP•2y ago

i dont see any output on my side..

ero•2y ago

show your code now

madogumglyniumOP•2y ago

using Process process = new()
            {
                StartInfo = new()
                {
                    FileName = path,
                    UseShellExecute = false,
                    RedirectStandardOutput = true,
                    CreateNoWindow = true
                }
            };

            process.OutputDataReceived += new DataReceivedEventHandler((sender, e) =>
            {
                if (string.IsNullOrEmpty(e.Data))
                    return;

                BeginInvoke(() =>
                {
                    tboxConsole.AppendText(e.Data + Environment.NewLine);
                    tboxConsole.Refresh();
                });
            });

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

using Process process = new()
            {
                StartInfo = new()
                {
                    FileName = path,
                    UseShellExecute = false,
                    RedirectStandardOutput = true,
                    CreateNoWindow = true
                }
            };

            process.OutputDataReceived += new DataReceivedEventHandler((sender, e) =>
            {
                if (string.IsNullOrEmpty(e.Data))
                    return;

                BeginInvoke(() =>
                {
                    tboxConsole.AppendText(e.Data + Environment.NewLine);
                    tboxConsole.Refresh();
                });
            });

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