What is the SIGUSR2 signal, and what effect does it have?

I am CentOS 7.4 on Dell servers. I'm running this command in a script: kill -SIGUSR2 ps -ef|grep ${rule}/etc/suricata/suricata.yaml|grep -v grep|awk '{ print $2 }' The ps part here grabs PID, but what does SIGUSR2 do? I see it's "user-defined"; how does that translate into actions?