This post will explore how to get bandwidth usage alert from your system by the email, this simple script developed by shell. Before execute it you need to install  vnstat and mail packages.

VNSTAT Command for getting bandwdith usage report.

MAIL   Send alert mail from the system.

Create a file name  bandwidth.sh and add the below code and give execute permission to run.

#  touch bandwidth.sh

#  chmod +x bandwidth.sh


#!/bin/bash

stat=`vnstat | tail -1 | awk '{print $8}'`

IP=`/sbin/ifconfig eth0 | grep "inet addr" | awk -F: '{print $2}' | awk '{print $1}'`

TO_ADDRESS="alerts@thelinuxfaq.com"

SUBJECT="Bandwidth AVG Used"



#set bandwith limit in GiB size,

band=10



#get bandwith reports

   if [ $(echo "$stat >  $band" | bc) -ne 0 ]

    then

    echo $stat

    echo > /tmp/bandwidth.txt

    vnstat > /tmp/bandwidth.txt

    mail -s "$SUBJECT - $stat GiB in :$HOSTNAME-$IP" $TO_ADDRESS  < /tmp/bandwidth.txt

   else

       echo "None of the condition met"

   fi