Playing around with bash, at the university I have to manually set my internet configuration on a specific network. Thought let's automate it

change-gateway.sh

#!/bin/bash

set -xi

sudo ip addr add 172.16.4.99/22 dev eth0
GATEWAY=$(ip route show | grep default | awk '{ print $3}')
echo "Current default gateway: $GATEWAY"
if [ -z $GATEWAY ]
    then
        sudo ip route del default $GATEWAY
fi

sudo ip route add default via 172.16.4.1


echo "nameserver 166.111.8.28" | sudo tee -a /etc/resolv.conf
echo "Done.."