Linuxphile.org

Working as the TechGuy administrator I needed to create a shell script that would monitor disk usage. Doing this required several tweaks and learning the nuances of several shell commands. Below is the end result of this work. The script uses a combination of awk, egrep, cat, cut and mail commands.



The script is written to use a temporary file, temp.txt to store the messages when disk usage is above the limit I have set to monitor with the variable $error.


When the script first begins it sets the variables for the user to email and the error level, as well as deleting the temporary file if it exists. You can add mutiple recipients to the email users with something like:

emailUser="user1@email.com,user2@email.com"

Notice that the variables that are going contain numeric values have been set as integers using the typeset command.



Rather than use the df command to get the device names I've employed the use of the mount command, which with no parameters given will dump all mounted devices. I've then piped output of this command to egrep to make sure I only get the devices which are disk drives. The for loop then does a df on each device, cutting the output from characters 40 thru 42 to give the percentage, typeset as an integer. If that value is greater than the $error level previously set a messsage is appended to the temporary file.


At the end of the script, if the temporary file exists a mail message is composed and sent to the defined users in $emailUser. You'll notice that I made use of the $HOSTNAME variable in the subject of the email to make the script more portable. This script is used on 4 servers at TechGuy.


Hopefully you will find the script useful and it will save you time.

#!/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.
#
#       Copyright 2006 Daniel McCarthy
# BE SURE TO CHANGE THIS TO YOUR EMAIL ADDRESS ;) 
emailUser="dan@linuxphile.org"
typeset -i error="90"
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%" >> 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 Report for: $HOSTNAME" $emailUser
fi