linux查看网口流量的脚本

通过本脚本，发现bash确实在算术运算方面比老的shell要强大，为此需要开始学习bash，以利用它强大的功能。不过bash中的for语句功能和c中差异比较大。


# cat stream

#! /bin/bash
# Write by Neil.xu  qq:37391319 email: [e-mail]
# 2008-8-19 we need to monitor streams of LTS channels, so write this script
typeset in in_old dif_in dif_in1 dif_out1
typeset out out_old dif_out

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))
         dif_in1=$((dif_in * 8 / 1024 / 1024 ))
         dif_out=$((out-out_old))
         echo "                                         IN: ${dif_in} bytes     OUT: ${dif_out} bytes "
         dif_out1=$((dif_out * 8 / 1024 / 1024 ))
         echo "IN: ${dif_in1} mbps    OUT: ${dif_out1} mbps"
         in_old=${in}
         out_old=${out}
done


运行效果：
# ./stream
                                                IN: 349179 bytes     OUT: 1363936 bytes
IN: 2 mbps    OUT: 10 mbps
                                                IN: 349612 bytes     OUT: 1361852 bytes
IN: 2 mbps    OUT: 10 mbps
                                                IN: 348684 bytes     OUT: 1358952 bytes
IN: 2 mbps    OUT: 10 mbps
                                                IN: 349998 bytes     OUT: 1359092 bytes