purge OSX wifi SSIDs

#!/bin/bash

# John Slee <indigoid@gmail.com>

keep_until="heart of gold"

get_wifi_interface() {
	networksetup -listallhardwareports | sed -n '/Wi-Fi$/,/^Device/ { s/.*\(en[0-9]\)$/\1/p; }'
}

get_wifi_ssids() {
	IFS="\\012" networksetup -listpreferredwirelessnetworks $1 \
		| sed -n "1,/$2/d; s/^[[:space:]]*//; p"
}

if=$(get_wifi_interface | head -1)

# quick sanity check
if ! /sbin/ifconfig $if > /dev/null 2>&1 ; then
	echo "can't find your wifi, halp"
	exit 1
fi

if [ "$1" == "no-really" ] ; then
	really=1
else
	echo "Dry-run. Pass 'no-really' on the commandline to actually remove SSIDs."
	echo
fi

get_wifi_ssids "$if" "$keep_until" | while read ssid ; do
	if [ "$really" == 1 ] ; then
		sudo networksetup -removepreferredwirelessnetwork "$if" "$ssid"
	else
		echo "Found unwanted SSID: $ssid"
	fi
done

Probably need to check that en0 is your wireless interface (mine's en1) :) It'll just have a whine if it's not.

yaleman$ networksetup -listpreferredwirelessnetworks en0
en0 is not a Wi-Fi interface.

Fixed!