#!/bin/sh

#
# Determine if Interface is up
#
interface_is_up() {
    [ -n "$(ip link ls dev $1 | grep -e '[<,]UP[,>]')" ]
}

case $# in
    1)
	timeout=60
	;;
    2)
	timeout=$2
	;;
    *)
	echo "usage: $(basename $0) <interface> [ <timeout> ]"
	exit 2
	;;
esac

while [ $timeout -gt 0 ] && ! interface_is_up $1; do
    sleep 1
    timeout=$(( $timeout - 1 ))
done