public static int sendSignal(int pid, int signal) {
    if (pid <= 0) {
      throw new IllegalArgumentException("Invalid PID: " + pid + " (killing all user processes in one shot is prohibited here)");
    }
    checkCLib();
    return Java8Helper.C_LIB.kill(pid, signal);
  }
public static int sendSignal(int pid, int signal)