How To Keep Track On Disk Usage @Linux

#! /bin/bash
# chetan.muneshwar@gmail.com
# script to get disk space status on multiple instances and alert Admin


bulk_data=(`df -Ph | grep -r '/' | awk '{ printf "%s-%s-%s-%s ",$3,$4,$5,$6  }'`)

for ((  i = 0 ;  i < ${#bulk_data[*]};  i++  ))
            do
threshold="`echo ${bulk_data[i]}|cut -d "-" -f 3|cut -d "%" -f 1` "


        if [ $threshold -le 0 ] ; then
                shm_val="`echo ${bulk_data[i]}|grep -r 'shm'`"
                if [ "$shm_val" == "" ] ; then
                    echo "SERVER ${bulk_data[i]} " | mail -s " Disk vol fuLL ISHY-SERVER " chetan.muneshwar@labs.net -c shrikant.lokhande@labs.net
                else
                   echo ""
                fi
        else
           if [ $threshold -le 90 ] ;then
             echo ""
           else
                  echo "SERVER  ${bulk_data[i]} " | mail -s " Disk vol warning ISHY-SERVER   " chetan.muneshwar@labs.net -c shrikant.lokhande@labs.net
            fi
        fi
done
Finally add cronjob : * * * * * /usr/bin/DISK