linux监控网卡流量脚本

#!/bin/bash
in_old=$(cat /proc/net/dev | grep eth0 | sed 's=^.*:==' | awk '{print $1}')
out_old=$(cat /proc/net/dev | grep eth0 | sed 's=^.*:==' | awk '{print $9}')

while true
do
    sleep 1
    in=$(cat /proc/net/dev | grep eth0 | sed 's=^.*:==' | awk '{print $1}')
    out=$(cat /proc/net/dev | grep eth0 | sed 's=^.*:==' | awk '{print $9}')

    dif_in=$((in-in_old))
    if [ $dif_in -lt 1024 ]
    then
        dif_in1="$((dif_in)) B/s"
    elif [ $dif_in -gt 1048576 ]
    then
        dif_in1="$((dif_in/1024/1024)) MB/s"
    else
        dif_in1="$((dif_in/1024)) KB/s"
    fi

    dif_out=$((out-out_old))

    if [ $dif_out -lt 1024 ]
    then
        dif_out1="$((dif_out)) B/s"
    elif [ $dif_out -gt 1048576 ]
    then
        dif_out1="$((dif_out/1024/1024)) MB/s"
    else
        dif_out1="$((dif_out/1024)) KB/s"
    fi

    echo "IN:${dif_in1}   OUT:${dif_out1}"

    in_old=${in}
    out_old=${out}
done