this is actually 2 questions
i've seen ctrl_interface= used in many wpa_supplicant.conf files as of late, but i don't understand its purpose. i understand that ctrl_interface_group= gives a group permission over the ctrl_interface but nothing else.
also, i usually see it referenced to /var/run/wpa_supplicant
in /var/run i see several items ending in .pid. so my 2nd question is what is the purpose of /var/run i googled this, but i didn't understand what i was reading.