Are the Pi and the Mac in the same network? In that case, I just used arp -a to find it. There's a number of other methods though, listed here: http://apple.stackexchange.com/questions/19783/how-do-i-know-the-ip-addresses-of-other-computers-in-my-network?rq=1https://apple.stackexchange.com/questions/19783/how-do-i-know-the-ip-addresses-of-other-computers-in-my-network?rq=1
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