This will monitor the Disk space of a Linux system and send an email to ADMIN . Admin , and Thresold is a variable , so that it can be change accordingly.
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#!/bin/bash
# This script determines the percentage of disk usage.
# If that percentage is greater than 90% a user is emailed
# a report notifying them of the usage.
#
emailUser=”it.support@au.specsavers.com,brandont@au.specsavers.com”
typeset -i error=”70″
if [ -e temp.txt ]; then
rm temp.txt
fi
for disc in `mount| egrep ‘^/dev’ | egrep -iv ‘cdrom|proc|sys|pts’ |awk ‘{print $3}’`
do
typeset -i discUsage=`df -h $disc|cut -c40-42|grep -i [^a-z]`
if [ “$discUsage” -ge “$error” ]; then
echo “Disc usage for $disc is at $discUsage. Need your attention !!%” >> temp.txt
fi
done
if [ -e temp.txt ]; then
message=`cat temp.txt`
fi
if [ ${#message} -gt 0 ]; then
cat temp.txt | mail -s “Disc Usage exceed 70% for : $HOSTNAME” $emailUser
fi
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Mohammad Alam - K'Base 
This is modified to have option to exclude Pertion to Monitor.
#!/bin/sh
# set -x
# Shell script to monitor or watch the disk space
# It will send an email to $ADMIN, if the (free available) percentage of space is >= 90%.
# ————————————————————————-
# Set admin email so that you can get email.
ADMIN=”compiere@au.specsavers.com,it.support@au.specsavers.com”
# set alert level 90% is default
ALERT=90
# Exclude list of unwanted monitoring, if several partions then use “|” to separate the partitions.
# An example: EXCLUDE_LIST=”/dev/hdd1|/dev/hdc5″
EXCLUDE_LIST=”/mnt/minosShared|/archive”
#
#::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
#
function main_prog() {
while read output;
do
#echo $output
usep=$(echo $output | awk ‘{ print $1}’ | cut -d’%’ -f1)
partition=$(echo $output | awk ‘{print $2}’)
if [ $usep -ge $ALERT ] ; then
echo “Running out of space \”$partition ($usep%)\” on server $(hostname), $(date)” | \
mail -s “Alert: Out of disk space $usep% on $(hostname)” $ADMIN
fi
done
}
if [ “$EXCLUDE_LIST” != “” ] ; then
df -H | grep -vE “^Filesystem|tmpfs|cdrom|${EXCLUDE_LIST}” | awk ‘{print $5 ” ” $6}’ | main_prog
else
df -H | grep -vE “^Filesystem|tmpfs|cdrom” | awk ‘{print $5 ” ” $6}’ | main_prog
fi