Easily set routing table to allow the use of 2 different network connections

routy.sh

#!/usr/bin/env bash

# This script helps you easily set routing tables to allow you use
#  two different network connections.
#  I use this to use My mobile broadband connection to access internet
#  while retaining access to office network for internal stuff.
# Use 'route -n' to view current routing table.

#set your preferred defaults here
PRIMARY_GW="192.168.8.1"
SECONDARY_GW="192.168.7.1"

function usage(){
    echo "$0 --flush"
    echo "$0 --set [primary gateway] [secondary gateway]"
    exit 1
}

function setroutes(){
    sudo route add -net 192.168.0.0 netmask 255.255.0.0 gw $2 
    sudo route add default gw $1
    sudo route del default gw $2
    exit 0
}

case "$1" in
    -f|--flush)
        sudo ip route flush table main
    ;;
    -s|--set)
        if [ $# == 3 ];then
            PRIMARY_GW=$2
            SECONDARY_GW=$3
        fi

        setroutes $PRIMARY_GW $SECONDARY_GW
    ;;
    -h|--help|*)
        usage
    ;;
esac