code: def exec_notebook_daemon_command(self, name, cmd, port=0):
          
          cmd = self.get_notebook_daemon_command(name, cmd, port)
  
          # Make all arguments explicit strings
          cmd = [str(arg) for arg in cmd]
  
          logger.info("Running notebook command: %s", " ".join(cmd))
          # print("XXX - DEBUG - Running notebook command:", " ".join(cmd))
  
          # Add support for traceback dump on stuck
          env = os.environ.copy()
          env["PYTHONFAULTHANDLER"] = "true"
  
          p = subprocess.Popen(cmd, stderr=subprocess.PIPE, stdout=subprocess.PIPE, env=env)
          time.sleep(0.2)
          stdout, stderr = p.communicate()
  
          if b"already running" in stderr:
              raise RuntimeError("Looks like notebook_daemon is already running. Please kill it manually pkill -f notebook_daemon. Was: {}".format(stderr.decode("utf-8")))
  
          if p.returncode != 0:
              logger.error("STDOUT: %s", stdout)
              logger.error("STDERR: %s", stderr)
  
              raise RuntimeError("Could not execute notebook command. Exit code: {} cmd: {}".format(p.returncode, " ".join(cmd)))
  
          return stdout
docs: Run a daemon script command.