BLE scan on Raspberry Pi does not work in Java via ProcessBuilder / Runtime

Question

I would like to scan the BLE devices on the Raspberry Pi in Java. I used the posted BLE scanning script (ibeacon_scan.sh) from the answer of jjnebeker. It works really great, when I start it on my UNIX laptop with the following Java code:

public void init(String[] commands){
  // commands -> {"/bin/bash","-c","/<PATH>/ibeacon_scan.sh"}
  ProcessBuilder processBuilder = new ProcessBuilder(commands);
  processBuilder.redirectErrorStream(true);
  Process process = processBuilder.start();
  createAndStartProcessOutputHandlerThread(process);
}

private Thread createAndStartProcessOutputHandlerThread(Process process) {
  Thread thread = new Thread(new Runnable() {
    public void run() {
      Scanner scan = null;
      try {
        scan = new Scanner(process.getInputStream());
        while (true) {
            if(scan.hasNext()){
                String line = scan.nextLine();
                LOG.info("LINE: ", line);
            }
        }
    } finally {
        if(scan != null) {
            scan.close();
        }
    }
  });
   thread.start();
   return thread;
}

I started the script as sudo on the Raspberry Pi and I get only empty lines but no other informations as exceptions or something else :(

EDIT: The script runs correctly when I execute it in the shell on the Raspberry Pi.

I have no idea how to fix this problem. Can you help me, please?