Disk Space Monitoring Script for Linux Operating system

When ever disk space is going to low the following script will send a mail to the user show disk space low at which hostname and disk.

Script:

#!/bin/sh
#=================================================================================================

# Script Title  : Disk Space Monitoring
# Version       : 1.0
# Purpose       : Shell script to monitor disk space
# It will send an email to provided email IDs, if available percentage of free space is > /tmp/diskspace/space.txt
        echo "Date- $dt" >> /tmp/diskspace/space.txt
        echo "IP Address -`/sbin/ifconfig | egrep -o '([0-9]{1,3}\.){3}[0-9]{1,3}' | egrep -v '255|(127\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3})'`"  >> /tmp/diskspace/space.txt
        echo "Hostname - $(hostname)"  >> /tmp/diskspace/space.txt

df -H | grep -vE '^Filesystem|tmpfs|cdrom' | awk '{ print $5 " " $6 }' | while read output;
do
  usep=$(echo $output | awk '{ print $1}' | cut -d'%' -f1  )
  partition=$(echo $output | awk '{ print $2 }' )
# Checks if disk free is between 75% and 85%
  if [ $usep -gt 75 ] && [ $usep -le 85 ]; then
        echo "File System -$partition"  >> /tmp/diskspace/space.txt
        echo "Percent Used - $usep%"  >> /tmp/diskspace/space.txt
mailx -s "WARNING !! Low disk space on $(hostname)- $(date)" $EMAIL  > /tmp/diskspace/space.txt
        echo "Percent Used - $usep%"  >> /tmp/diskspace/space.txt
mailx -s "CRITICAL !! Low disk space on $(hostname)- $(date)" $EMAIL  > /tmp/diskspace/space.txt
echo "Percent Used - $usep%"  >> /tmp/diskspace/space.txt
mailx -s "HIGH CRITICAL !! Low disk space on $(hostname)- $(date)" $EMAIL  < space.txt
        fi
    fi
done