How do I send ctrl+c to a process in c#?

Question

I'm writing a wrapper class for a command line executable. This exe accepts input from stdin until i hit ctrl+c in the command prompt shell, in which case it prints output based on the input to stdout. I want to simulate that ctrl+c press in c# code, sending the kill command to a .Net process object. I've tried calling Process.kill(), but that doesn't seem to give me anything in the process's StandardOutput StreamReader. Might there be anything I'm not doing right? Here's the code I'm trying to use:

ProcessStartInfo info = new ProcessStartInfo(exe, args);
info.RedirectStandardError = true;
info.RedirectStandardInput = true;
info.RedirectStandardOutput = true;
info.UseShellExecute = false;
Process p = Process.Start(info);

p.StandardInput.AutoFlush = true;
p.StandardInput.WriteLine(scriptcode);

p.Kill(); 

string error = p.StandardError.ReadToEnd();
if (!String.IsNullOrEmpty(error)) 
{
     throw new Exception(error);
}
string output = p.StandardOutput.ReadToEnd();

however output is always empty even though I get data back from stdout when I run the exe manually. edit: this is c# 2.0 btw

Answer 1

Try actually sending the Key Combination Ctrl+C, instead of directly terminating the process:

 [DllImport("user32.dll")]
        public static extern int SendMessage(
              int hWnd,      // handle to destination window
              uint Msg,       // message
              long wParam,  // first message parameter
              long lParam   // second message parameter
              );

Look it up on the MSDN, you should find what you need there in order to send the Ctrl+Key combination... I know that the message you need for sending Alt+Key is WM_SYSTEMKEYDOWN and WM_SYSTEMKEYUP, can't tell you about Ctrl...

Answer 2

@alonl: The user is attempting to wrap a command-line program. Command-line programs don't have message pumps unless they are specifically created, and even if that was the case, Ctrl+C doesn't have the same semantics in a Windows-environment application (copy, by default) as it does in a command-line environment (Break).

I threw this together. CtrlCClient.exe simply calls Console.ReadLine() and waits:

        static void Main(string[] args)
        {
            ProcessStartInfo psi = new ProcessStartInfo("CtrlCClient.exe");
            psi.RedirectStandardInput = true;
            psi.RedirectStandardOutput = true;
            psi.RedirectStandardError = true;
            psi.UseShellExecute = false;
            Process proc = Process.Start(psi);
            Console.WriteLine("{0} is active: {1}", proc.Id, !proc.HasExited);
            proc.StandardInput.WriteLine("\x3");
            Console.WriteLine(proc.StandardOutput.ReadToEnd());
            Console.WriteLine("{0} is active: {1}", proc.Id, !proc.HasExited);
            Console.ReadLine();
        }

My output seems to do what you want:

4080 is active: True

4080 is active: False

Hope that helps!

(To clarify: \x3 is the hex escape sequence for the hex character 3, which is ctrl+c. It's not just a magic number. ;) )

Answer 3

I've actually just figured out the answer. Thank you both for your answers, but it turns out that all i had to do was this:

p.StandardInput.Close()

which causes the program I've spawned to finish reading from stdin and output what i need.