#!/bin/bash
#----------------------------------------------------------------------------
# Check previous netstat output against current netstat output to determine
# if there are packet receive errors.  We have to do this because the counters
# are only cleared when the server is rebooted.
#----------------------------------------------------------------------------

NOW=`date`
echo "$NOW"
emailaddress=emailadr@yoursite.com
logfile=/tmp/1.out


ARGCOUNT=1

if [ $# -ne "$ARGCOUNT" ]
then
  echo "Usage: `basename $0` <$email-address>"
  exit 1
fi


#Check if previous Netstat -i output file exist

if [ -s $logfile ]
then

    OLDNETSTAT=`netstat -i | awk "{print $6}"  | cut -f 15,19,20 -d ' '`
    netstat -i |grep "RX-DRP" | awk "{print $6}" > $logfile  #take a new netstat snapshot
    NOWNETSTAT=`netstat -i | awk "{print $6}"  | cut -f 15,19,20 -d ' '`

    echo "OLDNETSTAT=$OLDNETSTAT"
    echo "NOWNETSTAT=$NOWNETSTAT"

    if [ $OLDNETSTAT -lt $NOWNETSTAT ]
    then
        NUMDROPS=$(( NOWNETSTAT - OLDNETSTAT ))
        servername=`hostname -s`
        MYMESSAGE="WARNING: netstat -i: $NUMDROPS new "RX-DRP" error(s) on $servername"
        mail -s "$MYMESSAGE" $1 < /dev/null
    fi

else
   echo "Running command: netstat -i | awk "{print $6}"  | cut -f 15,19,20 -d ' ' > $logfile"

   netstat -i | awk "{print $6}"  | cut -f 15,19,20 -d ' ' > $logfile
fi