public class Youtube_Downloader {
       private static FileOutputStream fos = null;
      /******************************************************************************************/
      public static void main(String[] args) throws Exception {
            String s = null;
            File logFile = new File("ytlog.txt");
            fos = new FileOutputStream(logFile, true); //true = append
            try {
                Process p = Runtime.getRuntime().exec("ps -ef ");
                BufferedReader stdInput = new BufferedReader(new InputStreamReader(p.getInputStream()));
                BufferedReader stdError = new BufferedReader(new InputStreamReader(p.getErrorStream()));
                boolean youtube_dl_running_flag = false;
                while ((s = stdInput.readLine()) != null) {
                    if(s.indexOf("youtube-dl") > -1) {
                        log(s);
                        youtube_dl_running_flag = true;
                        System.exit(-1);
                    }
                }
                if(youtube_dl_running_flag == false) {
                    log("youtube-dl is not running.  launching now...");
                    Process p2 = Runtime.getRuntime().exec("youtube-dl https://www.youtube.com/watch?v=0SZw8jpfAk0");
                    log("Process launched...");
                    BufferedReader stdInput2 = new BufferedReader(new InputStreamReader(p2.getInputStream()));
                    BufferedReader stdError2 = new BufferedReader(new InputStreamReader(p2.getErrorStream()));
                    int exitVal = p2.waitFor();
                    log("WaitFor() complete.  exitVal=" + exitVal );
                    while ((s = stdInput2.readLine()) != null) {
                        System.out.println(s);
                    }
                    while ((s = stdError2.readLine()) != null) {
                        System.out.println(s);
                    }
                }
            } catch (IOException e) {
                e.printStackTrace();
                System.exit(-1);
            } finally {
                fos.close();
            }
      }
      /******************************************************************************************/
      public static void log(Object obj) throws Exception {
         fos.write((new Date() + " : " + obj.toString() + "\r\n").getBytes());
      }
    }