Connect to WiFi network using Mac Terminal

As of Snow Leopard (Mac OS X v10.6.x) and possibly earlier, you can do:

networksetup -setairportnetwork $INTERFACE $SSID $PASSWORD

Where...

• $INTERFACE is the "enX" style identifier for your AirPort card (usually en1, but it's en0 on MacBook Airs and en2 on Mac Pros, and can vary for other reasons as well)
• $SSID is your network name, such as "Simon's SSID". Enclose it in quotes if it contains spaces.
• $PASSWORD is your WEP, WPA-PSK, or WPA2-PSK password.

If you look at the man page or help/usage statement for networksetup you'll see that it has other AirPort-related subcommand for getting or setting the power state (AirPort card on/off), and for managing the Preferred Networks list and 802.1X profiles (if your network uses 802.1X, such as a WPA Enterprise or WPA2 Enterprise network would).

Figured it out:

sudo airport -A

Here is a little guide on using airport in the Command Line

Apparently you can use

$ airport 

as a command. I would try

$ airport -help

and see if it brings up some options.

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