#!/bin/sh

/sbin/ip monitor link | while read -r line
do

    echo $line
    iface=$(echo $line | sed -ne 's/[^ ]* ([^ ]*): .* state ([^ ]*).*/1/p')
    state=$(echo $line | sed -ne 's/[^ ]* ([^ ]*): .* state ([^ ]*).*/2/p')
    if [ "$iface" != "" ] ; then
        echo "$iface is $state"
        if [ -f /tmp/${iface}.metric ] ; then
                echo "updating default route for ${iface}"
                if [ "$state" = "DOWN" ] ; then
                        ip route del default dev "${iface}"
                else
                        ip route add default dev "${iface}" metric `cat /tmp/${iface}.metric`
                fi
        fi
    fi
done