ubuntu server 18.04 setup wifi

u@ubuntu:~$ ifconfig wlan0 up

u@ubuntu:~$ wpa_passphrase wifiname password | sudo tee /etc/wpa_supplicant.conf

u@ubuntu:~$ sudo wpa_supplicant -B -c /etc/wpa_supplicant.conf -i wlan0

// get ip

u@ubuntu:~$ sudo dhclient wlan0

//test

u@ubuntu:~$ ping 8.8.8.8



make it auto connect wifi.

raspberry pi 4 won't bring up wlan0 on boot.

$ sudo apt-get ifupdown

$ sudo vim /etc/rc.local


edit /etc/rc.local

u@ubuntu:~$ cat /etc/rc.local
ifup wlan0

edit /etc/network/interfacs

u@ubuntu:~$ cat /etc/network/interfaces
# ifupdown has been replaced by netplan(5) on this system.  See
# /etc/netplan for current configuration.
# To re-enable ifupdown on this system, you can run:
#    sudo apt install ifupdown

auto wlan0
iface wlan0 inet dhcp
wpa-conf /etc/wpa_supplicant.conf