You can use one of the following to retrieve the process id (pid) of Suricata
Have Suricata save its pid into a pidfile by starting Suricata in “daemon mode” (with -D) or using the command line option --pidfile
On Linux, pidof suricata will return Suricata’s process identifier.
When shutting down gracefully, all of the Napatech streams created by Suricata will be closed. Are you referring to these streams or the one that the ntservice process creates?