Disk Space monitoring

check_disk_space.sh

#!/bin/bash

LIMIT='90'
DIR='/'
MAILTO='[email protected]'
SUBJECT="MySite disk usage reached above $LIMIT%"
MAILX='mailx'
which $MAILX > /dev/null 2>&1
if ! [ $? -eq 0 ]
then
          echo "Please install $MAILX"
          exit 1
fi
cd $DIR
USED=`df . | awk '{print $5}' | sed -ne 2p | cut -d"%" -f1`
if [ $USED -gt $LIMIT ]
then
      df -h | $MAILX -s "$SUBJECT" "$MAILTO"
fi