1. configure wifi information.

    ubuntu@ubuntu:~$ cat /etc/wpa_supplicant/wpa_supplicant.conf
    netwokr={
       ssid="cicso"
       psk="ubunut12345"
    }
    
  2. specify configure file and network interface.

    ubuntu@ubuntu:~$ cat /lib/systemd/system/wpa_supplicant.service
    .....
    [Service]
    ExecStart=/sbin/wpa_supplicant -u -s -o /run/wpa_supplicant/ -c /etc/wpa_supplicant/wpa_supplicant.conf -i wlan0
    .....