#!/bin/bash

get_ip(){
ipv4=$(ifconfig $interface | grep -Eo 'inet (addr:)?([0-9]*\.){3}[0-9]*' | grep -Eo '([0-9]*\.){3}[0-9]*' | grep -v '127.0.0.1')
}

restart_if(){
sudo ip link set eth2 down
sleep 20
sudo ip link set eth2 up
sleep 1
get_ip

while [[ ! $ipv4 =~ $ip  ]]; do
	sleep 1
	get_ip
done
}

interface='eth2'
ip="([0-9]{1,3}.){4}"
regexp="^([0-9]{1,3}\.){2}${1}"
counter=1

get_ip

while [[ ! $ipv4 =~ $regexp ]]; do
	echo "no.: $counter, ip: $ipv4"
	counter=$((counter + 1))
	restart_if
done

echo 'Done'
echo "new ip: $ipv4"