#!/bin/sh
# this script was initially written for Redhat/CentOS
# file is /etc/cron.daily/diskAlert.cron
# requires enabling outgoing sendmail from localhost to a valid 
# smtp server, which is usually disabled by default
ADMIN="jausten@adomain.com,another@adomain.com"
THRESHOLD=90

df -PkH | grep -vE '^Filesystem|tmpfs|cdrom|media' | awk '{ print $5 " " $6 }' | while read output;
do
  usep=$(echo $output | awk '{ print $1}' | cut -d'%' -f1 )
  partition=$(echo $output | awk '{print $2}' )
  if [ $usep -ge $THRESHOLD ]; then
    echo "Running out of space \"$partition ($usep%)\" on $(hostname) as on $(date)" |
    mail -s "Alert: Almost out of disk space $usep%" $ADMIN
  fi
done