How to connect to WiFi using command line Ubuntu, Debian etc.

Tried to upgrade to Ubuntu 15.10 Beta 2, rebooted  and my system was broken. Could not connect to LAN, so my only option was to connect to Wifi via command line to hopefully repair my system.

This is what I did.

First, open a terminal:

Ctrl-Alt-T

If you got WPA like me you need wpa_supplicant to set it up, because iw can only handle WEP.

To bring up your wireless device (most likely wlan0):

sudo -s
ifconfig wlan0 up
#now scan for available wifi networks and note the ssid of your device
iwlist wlan0 scan

In /etc/wpa_supplicant.conf we need to put our ssid and password:

nano /etc/wpa_supplicant.conf

Example config:

network={

                     ssid="ssid"

                     psk="wifi password"

}

Ctrl + A to close and save.
To connect:

sudo wpa_supplicant -B -iwlan0 -c/etc/wpa_supplicant.conf -Dwext

Open a second tab/terminal:

sudo dhclient wlan0

Your connection should now work!