Monitor Oracle PaaS VM machine disk usage shell script

0 * * * *  sh /home/oracle/dbascripts/monitor_disk.sh


#!/bin/bash
echo `date` >> /tmp/cron.txt
LIMIT='90'
#Here we declare variable LIMIT with max of used space

DIR='/u03'
#Here we declare variable DIR with name of directory

MAILTO='M.Allam@tahaluf.ae,n.abuaqoulah@tahaluf.ae,m.almasri@tahaluf.ae'

#Here we declare variable MAILTO with email address
SUBJECT="Backup Mount point $DIR disk usage"

#Here we declare variable SUBJECT with subject of email
MAILX='mailx'

#Here we declare variable MAILX with mailx command that will send email
which $MAILX > /dev/null 2>&1

#Here we check if mailx command exist
if ! [ $? -eq 0 ]
#We check exit status of previous command if exit status not 0 this mean that mailx is not installed on system

then
          echo "Please install $MAILX"
#Here we warn user that mailx not installed
          exit 1
#Here we will exit from script
fi
cd $DIR
#To check real used size, we need to navigate to folder
USED=`df -Pl  | grep $DIR  | grep "^/dev" | awk '{print $5}' | sed "s/%//"`
#This line will get used space of partition where we currently, this will use df command, and get used space in %, and after cut % from value.
if [[ $USED -gt $LIMIT ]]
#If used space is bigger than LIMIT
then
      echo "Current Disk Space utilization is $USED% which needs your attention" | $MAILX -s "$SUBJECT" "$MAILTO"
#This will print space usage by each directory inside directory $DIR, and after MAILX will send email with SUBJECT to MAILTO
fi