Quickly setup multiple wifi connections on your raspberry pi through the command lineStep by step illustrated guide showing you how to setup your wireless connection if you only have access to the terminalSetting it up using just the /etc/network/interfaces files can work but you will run into issues when you need multiple connections or if you ever do access the desktop environment.  Setting it up using wpa supplicant will be more reliable in the long run

Source: How-To: Raspberry Pi multiple WiFi setup through the command line