interface speed script

speed.sh

#!/bin/bash

[ -z "$1" ] && { echo "usage: $0 interface"; exit; }
[ -d /sys/class/net/$1 ] || { echo "interface $1 doesn't exist."; exit; }

PREFIX=(" " "K" "M" "G" "T")

# update interval in seconds
INTERVAL=5

# use 30 samples for the crude rolling avg
N=30

get_multiplier() {
        value=$1
        index=0
        while [ $value -gt 8192 ]; do
                remainder=$(( value % 1024 ))
                value=$(( value / 1024 ))
                ((index++))
        done
        if [ $remainder > 512 ]; then
                ((value++))
        fi
        echo $value ${PREFIX[$index]}
}

rolling_avg() {
        avg=$1
        new_sample=$2

        # first sample?
        if [ $avg -gt 0 ]; then
                avg=$((avg - avg / N))
                avg=$((avg + $new_sample / N))
        else
                avg=$new_sample
        fi
        echo $avg
}


IF=$1
LEN=${#IF}
LOOPS=0

ARBPS=-1
ARPPS=-1
ATBPS=-1
ATPPS=-1

while true; do
        # packets
        RP1=$(cat /sys/class/net/$IF/statistics/rx_packets)
        TP1=$(cat /sys/class/net/$IF/statistics/tx_packets)
        # bytes
        RB1=$(cat /sys/class/net/$IF/statistics/rx_bytes)
        TB1=$(cat /sys/class/net/$IF/statistics/tx_bytes)

        sleep $INTERVAL

        # packets
        RP2=$(cat /sys/class/net/$IF/statistics/rx_packets)
        TP2=$(cat /sys/class/net/$IF/statistics/tx_packets)
        # bytes
        RB2=$(cat /sys/class/net/$IF/statistics/rx_bytes)
        TB2=$(cat /sys/class/net/$IF/statistics/tx_bytes)

        TXPPS=$(( (TP2 - TP1) / INTERVAL))
        RXPPS=$(( (RP2 - RP1) / INTERVAL))
        TXBPS=$(( (TB2 - TB1) / INTERVAL))
        RXBPS=$(( (RB2 - RB1) / INTERVAL))
        read TBPS UTBPS <<<$(get_multiplier $TXBPS)
        read RBPS URBPS <<<$(get_multiplier $RXBPS)

        ATBPS=$(rolling_avg $ATBPS $TXBPS)
        ATPPS=$(rolling_avg $ATPPS $TXPPS)
        ARBPS=$(rolling_avg $ARBPS $RXBPS)
        ARPPS=$(rolling_avg $ARPPS $RXPPS)
        read TABPS UATBPS <<<$(get_multiplier $ATBPS)
        read RABPS UARBPS <<<$(get_multiplier $ARBPS)

        printf  "%s: TX %4d %1sBps %6d pps \t Avg: %4d %1sB/s %6d pps\n" \
          $IF      $TBPS "$UTBPS" $TXPPS $TABPS "$UATBPS" $ATPPS
        printf "%*s  RX %4d %1sBps %6d pps \t Avg: %4d %1sB/s %6d pps\n" \
          $LEN " " $RBPS "$URBPS" $RXPPS $RABPS "$UARBPS" $ARPPS
done