#!/bin/bash
if [ ! [ $0 =  2 ] ]
then
        echo "Use: bla.sh <interface> <up|down>"
        exit 1
fi

if [ [ $2 = 'up' ] ]
then
        i=2
else
        i=10
fi

echo "$((`cat /proc/net/dev | grep $1 | awk "{ print $i }'"  / 1024))kb"