[arch-general] Exiting wpa_supplicant

Dear list, I try to write a small shellscript that (dis-)connects me with / from the WLAN of my university. I use wpa_supplicant in combination with the -B switch to establish the connection. After a pause of 10 seconds I pull an IP address by calling dhcpcd. My question (in context of the wlan-disconnect-script): how can I exit wpa_supplicant if it runs in the background ? Up to now it's done by "sudo killall wpa_supplicant" but I guess it's not the best way. Kind regards, Nelson.