#!/bin/bash 
while [ "1" ] 
do 
eth=$1 
RXpre=$(cat /proc/net/dev | grep $eth | tr : " " | awk '{print $2}') 
TXpre=$(cat /proc/net/dev | grep $eth | tr : " " | awk '{print $10}') 
sleep 1 
RXnext=$(cat /proc/net/dev | grep $eth | tr : " " | awk '{print $2}') 
TXnext=$(cat /proc/net/dev | grep $eth | tr : " " | awk '{print $10}') 
clear 
echo  -e  "/t RX `date +%k:%M:%S` TX" 
RX=$((${RXnext}-${RXpre})) 
TX=$((${TXnext}-${TXpre})) 
if [[ $RX -lt 1024 ]];then 
RX="${RX}B/s"
elif [[ $RX -gt 1048576 ]];then 
RX=$(echo $RX | awk '{print $1/1048576 "MB/s"}') 
else 
RX=$(echo $RX | awk '{print $1/1024 "KB/s"}') 
fi 
if [[ $TX -lt 1024 ]];then 
TX="${TX}B/s"
elif [[ $TX -gt 1048576 ]];then 
TX=$(echo $TX | awk '{print $1/1048576 "MB/s"}') 
else 
TX=$(echo $TX | awk '{print $1/1024 "KB/s"}') 
fi 
echo -e "$eth /t $RX   $TX " 
done