wait_for_iface() {
    local DEVICE=$1
    local TIMEOUT=10
    echo -n "Waiting for interface $DEVICE: "
    # Some systems don't have operstate. Seems to be hardware dependent
    [ ! -e "/sys/class/net/${DEVICE}/operstate" ] && usleep 10000
    if [ -e "/sys/class/net/${DEVICE}/operstate" ]; then
        while true; do
            # check linkstate
            [ "x$(cat "/sys/class/net/${DEVICE}/operstate")" == "xup" ] && break
            TIMEOUT=$(( $TIMEOUT - 1 )) # don't wait forever, the pcnet iface of vmware will never be "up" although it's working
            [ "$TIMEOUT" -le 0 ] && break
            # else
            echo -n "."
            usleep 500000
        done
    else
        # we really don't have a operstate .. then just wait a sec and hope for the best.
        sleep 1
    fi
    echo ".$(cat "/sys/class/net/${DEVICE}/operstate" 2>/dev/null)"
}
true