使用shell脚本计算Linux网卡流量，方法中最关键点：
ifconfig $eth_name | grep bytes | awk '{print $6}' | awk -F : '{print $2}'
通过ifconfig eth0|grep bytes 得到输入输出的流量。
/@rac2=>dd2$ifconfig eth0|grep bytes
RX bytes:1638005313300 (1.4 TiB) TX bytes:3408060482049 (3.0 TiB)
再将结果通过awk 得出所要的字段值。
固定时间得到这些值，在写个循环计算一下就能得到网卡流量。
完整代码：
代码一：
#!/bin/bash
# 统计网卡流量
# link：www.maopiaopiao.com
# date：2013/2/26
n=10
date
rm -rf /tmp/ifconfig_log
while (( $n >= 0 ))
do
n=$(($n - 1));
date >> /tmp/ifconfig_log
ifconfig eth1 >> /tmp/ifconfig_log
sleep 1
done
grep "RX bytes:" /tmp/ifconfig_log | awk -F"[:| ]" '{print $13}' | awk 'BEGIN{tmp=$1}{if(FNR > 1)print $1-tmp}{tmp=$1}'
代码二：
#!/bin/bash
if [ -n "$1" ]; then
eth_name=$1
else
eth_name="eth0"
fi
i=0
send_o=`ifconfig $eth_name | grep bytes | awk '{print $6}' | awk -F : '{print $2}'`
recv_o=`ifconfig $eth_name | grep bytes | awk '{print $2}' | awk -F : '{print $2}'`
send_n=$send_o
recv_n=$recv_o
while [ $i -le 100000 ]; do
send_l=$send_n
recv_l=$recv_n
sleep 1
send_n=`ifconfig $eth_name | grep bytes | awk '{print $6}' | awk -F : '{print $2}'`
recv_n=`ifconfig $eth_name | grep bytes | awk '{print $2}' | awk -F : '{print $2}'`
i=`expr $i + 1`
send_r=`expr $send_n - $send_l`
recv_r=`expr $recv_n - $recv_l`
total_r=`expr $send_r + $recv_r`
send_ra=`expr ( $send_n - $send_o ) / $i`
recv_ra=`expr ( $recv_n - $recv_o ) / $i`
total_ra=`expr $send_ra + $recv_ra`
sendn=`ifconfig $eth_name | grep bytes | awk -F ( '{print $3}' | awk -F ) '{print $1}'`
recvn=`ifconfig $eth_name | grep bytes | awk -F ( '{print $2}' | awk -F ) '{print $1}'`
clear
echo "=================================================="
echo "Last second : Send rate: $send_r Bytes/sec Recv rate: $recv_r Bytes/sec Total rate: $total_r Bytes/sec"
echo "Average value: Send rate: $send_ra Bytes/sec Recv rate: $recv_ra Bytes/sec Total rate: $total_ra Bytes/sec"
echo "Total traffic after startup: Send traffic: $sendn Recv traffic: $recvn"
echo "=================================================="
done