How can launch an external process from java and still be able to interact with this process?

Question

My application should launch an external program to start recording the desktop. I am using a simple program: recordmydesktop. Launching the program works fine using ProcessBuilder.

My main issue is that I have to stop the recording. But I don't have access to the program anymore.

My first idea was to launch a terminal from java: bash did not stay open but xterm worked. First of all I would like to know why bash shell stay opened?

Then, I would like to find: How can I not use the xterm and still being able to stop the recording process? For example: send stop signal (Ctrl C) to the process.

Here is some sample code:

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

public class hh {

public static void main(String[] args) {
    try {
        Process process = new ProcessBuilder(new String[]{"/usr/bin/xterm" ,"recordmydesktop"}).start();
        InputStream processIS = process.getInputStream();
        InputStreamReader processISR = new InputStreamReader(processIS);
        BufferedReader processBR = new BufferedReader(processISR);
        String line;
        System.out.println("Output of the record process is: ");

        while ((line=processBR.readLine())!=null){
            System.out.print(line);
        }
        }
    catch (IOException e) {
        e.printStackTrace();
    }
}
}

Also, in this code, I am not able to get any line back. So my program does not know if the recordmydesktop is ok.

Ps: If you launch:

Process process = new ProcessBuilder(new String[]{"/usr/bin/xterm" ,"xterm"}).start();

Many xterm open instead of two. I create a loop that should not happen. This is not linked to my problem but if someone know the reason I am curious to know why.

Thanks for your help !

Answer 1

You can send a command to the process via the Output stream.

Process process ;
String command = "some command" ;
process.getOutputStream().writeBytes( command.getBytes() ) ;