With v6.0 suricata is now opened twice. It seems a stub is launched first then the main program. See below.
The problem with this is that the PID recorded the pid file is for the second invocation. Using that second PID with a “kill” command does not work; it is the first invocation’s PID that is required.
root 8564 0.1 0.1 17256 9012 pts/0 S 15:07 0:00 \_ /usr/bin/sudo /usr/local/bin/suricata -v --pidfile /d500g/var/run/suricata.pid -c /usr/local/etc/suricata/suricata.yaml -q 0
root 8569 100 2.8 248740 230800 pts/0 R 15:07 0:05 \_ /usr/local/bin/suricata -v --pidfile /d500g/var/run/suricata.pid -c /usr/local/etc/suricata/suricata.yaml -q 0