General :: Monitor Filesystems And Notify When The Status Is Warning >=80 And Critical >=90

I need to monitor my filesystems and get an email when the status is warning >=80 and critical >=90. I am not very good for scripting so I found an script but is not working for me This Red Hat Enterprise 5.0

Script
Code:
ADMIN="me@somewher.com"
# set alert level 90% is default
ALERT=90
df -H | grep -vE '^Filesystem|tmpfs|cdrom' | awk '{ print $5 " " $1 }' | while read output;
do
[Code]....