netspeed.sh

#!/bin/bash

sleep_time="${1:-1}"

while read int; do
    let "rx_bytes0+=$(<${int}statistics/rx_bytes)"
    let "tx_bytes0+=$(<${int}statistics/tx_bytes)"
done < <(ls -d /sys/class/net/*/)

sleep $sleep_time

while read int; do
    let "rx_bytes1+=$(<${int}statistics/rx_bytes)"
    let "tx_bytes1+=$(<${int}statistics/tx_bytes)"
done < <(ls -d /sys/class/net/*/)

let "rx_bps = ( rx_bytes1 - rx_bytes0 ) * 8 / ${sleep_time}"
let "tx_bps = ( tx_bytes1 - tx_bytes0 ) * 8 / ${sleep_time}"

echo rx_bps=$rx_bps
echo tx_bps=$tx_bps