Shell script to monitor or watch the disk space

diskspacecheck.sh

#!/bin/sh
#
# Shell script to monitor or watch the disk space
# It will send an email to $ADMINEMAIL, if the (free avilable) percentage 
# of space is >= 90% 
#
# Linux shell script to watch disk space (should work on other UNIX OSes)
# SEE URL: http://www.cyberciti.biz/tips/shell-script-to-watch-the-disk-space.html
#
# set admin email so that you can get email
ADMINEMAIL="username@emailserver.com"
# set from email address (optional)
FROMEMAIL=""
# set alert level 90% is default
ALERT=90
df -H | grep -vE '^Filesystem|tmpfs|cdrom' | awk '{ print $5 " " $1 }' | while read output;
do
  usep=$(echo "${output}" | awk '{ print $1}' | cut -d'%' -f1)
  partition=$(echo "${output}" | awk '{ print $2 }')
  if [ "${usep}" -ge ${ALERT} ]; then
    if [ -z ${FROMEMAIL} ]; then
      echo "Running out of space \"$partition (${usep}%)\" on $(hostname) as on $(date)" | 
        mail -s "Alert: Almost out of disk space - ${usep}%" ${ADMINEMAIL}
    else
      echo "Running out of space \"$partition (${usep}%)\" on $(hostname) as on $(date)" | 
        mail -r ${FROMEMAIL} -s "Alert: Almost out of disk space - ${usep}%" ${ADMINEMAIL}
    fi
  fi
done