实时流量监控

#!/bin/bash

function usage
{
        echo "Usage: $0 "
        echo "e.g. $0 eth0 2"
        exit 1
}
if [ $# -lt 2 ];then
        usage
fi

eth=$1
interval=$2

in_old=$(cat /proc/net/dev | grep -w $eth | sed -e "s/\(.*\)\:\(.*\)/\2/g" | awk '{ print $1 }' )
out_old=$(cat /proc/net/dev | grep -w $eth | sed -e "s/\(.*\)\:\(.*\)/\2/g" | awk '{ print $9 }' )

while true
do
    sleep ${interval}
    in=$(cat /proc/net/dev | grep -w $eth | sed -e "s/\(.*\)\:\(.*\)/\2/g" | awk '{ print $1 }' )
    out=$(cat /proc/net/dev | grep -w $eth | sed -e "s/\(.*\)\:\(.*\)/\2/g" | awk '{ print $9 }')
    sub_in=$(( ($in-$in_old)/$interval ))
    sub_out=$(( ($out-$out_old)/$interval ))
    echo "Recv rate: $((${sub_in}/1024)) KB/s   Sent rate:  $((${sub_out}/1024)) KB/s "
    in_old=${in}
    out_old=${out}
done
exit 0