#!/bin/bash

# ask to set static ip address
if [[ ! -d /etc/cloud ]]
    then
        if [[ ! -f /etc/network/interfaces.bak ]]
            then
                read -r -p "Set Static IP address? <y/N> " prompt
                    if [[ "${prompt,,}" =~ ^(y|yes)$ ]]
                        then
                            read -r -p "Enter Static IP Address with subnet prefix: " staticip
                            read -r -p "Enter Gateway IP Address: " gatewayip
                            read -r -p "Enter Primary DNS IP Address: " dnsip1
                            read -r -p "Enter Secondary DNS IP Address: " dnsip2
                            name=$(basename /sys/class/net/e*)
                                if [[ ! -f /etc/network/interfaces.bak ]]
                                    then
                                        cp /etc/network/interfaces /etc/network/interfaces.bak
                                fi
                            rm /etc/network/interfaces
                            cp /etc/network/interfaces.bak /etc/network/interfaces
                            sed -i "s,^iface $name inet dhcp*,iface $name inet static," /etc/network/interfaces
                            echo "        address $staticip" >> /etc/network/interfaces
                            echo "        gateway $gatewayip" >> /etc/network/interfaces
                                if [[ ! -f /etc/resolv.conf.bak ]]
                                    then
                                        cp /etc/resolv.conf /etc/resolv.conf.bak
                                fi
                            rm /etc/resolv.conf
                            echo "nameserver $dnsip1" >> /etc/resolv.conf
                            echo "nameserver $dnsip2" >> /etc/resolv.conf
                            ifdown $name
                            ifup $name
                    fi
        fi
fi