Switch DNS in Mac terminal, fast and with multiple options!

switch-dns-to.sh

#/bin/bash

NETWORK_SERVICE="Wi-Fi"
SERVERS=(google opendns uflix)
DNS_GOOGLE="8.8.8.8 8.8.4.4"
DNS_OPENDNS="208.67.222.222 208.67.220.220"
DNS_UFLIX="203.143.83.123 108.61.169.104"

if [ $# -ge 1 ]; then
	# get server name in uppercase
	SERVER=`echo $1 | tr '[:lower:]' '[:upper:]'`
else
	SERVER="NA"
fi

# try to find the dns addresses
DNS_VARNAME=`echo DNS_$SERVER`
eval SERVER_DNS=\$$DNS_VARNAME
len=${#SERVER_DNS}
if [ $len -eq 0 ]; then
	echo Usage: $0 server [network-service]
	echo Available servers: ${SERVERS[*]}
	exit 1
fi
echo Server: $SERVER = $SERVER_DNS

# use a different network service if specified
if [ $# -ge 2 ]; then
	NETWORK_SERVICE="$2"
fi
echo Network Service: $NETWORK_SERVICE

echo Changing DNS configuration now, you may be asked for password...
sudo networksetup -setdnsservers $NETWORK_SERVICE $SERVER_DNS

echo Have fun!