Setup WiFi (WPA2) connection on ubuntu via terminal

Edit:

/etc/network/interfaces

Add this: 

auto wlan0
iface wlan0 inet dhcp
wpa-ssid SSID
wpa-psk "password to wifi" 

Where: 

• wlan0 - name of the wireless interface 
• auto wlan0 - auto connect on start 

To connect manually run command:

ifup wlan0