#!/bin/sh
#
# Simple script to send email if usage on given filesystem exceeds given amount
#
# 2006 (c) Aleksandr Koltsoff
#

# check that we have all the necessary parameters to run
if [ $# -ne 3 ]; then
  echo "USAGE: checkfs.sh mount-point cut-off email-address"
  exit 1
fi

# copy command line parameters into local variables (easier to use)
MP=$1
CUTOFF=$2
EMAIL=$3
# we also get the hostname here so that the email can be more informative
HOSTNAME=`hostname`

# get usage in percentage
# 1) use df to get filesystem usage info on mount-point
# 2) delete all repeating spaces (so that we can use cut)
# 3) select fifth field (usage %)
# 4) remove the '%' so that we can use the number
USAGE=`df $MP | tail -1 | tr -s ' ' | cut -f5 -d' ' | tr -d '%'`
# echo $USAGE

# compare usage to cutoff point
# here we use [ foo ] so that shell will evaluate the contents
# as integers as opposed as text strings. we also use the -ge
# operator to test whether USAGE is greater or equal to CUTOFF
if [ $USAGE -ge $CUTOFF ]; then
  #echo "USAGE($USAGE) more than CUTOFF($CUTOFF)"
  # send email
  echo "Disk space usage on $HOSTNAME:$MP exceeded $CUTOFF% (now at $USAGE%)" \
    | mail -s "WARNING: $HOSTNAME:$MP disk space running low" $EMAIL
fi

# terminate with success code (this is a lie, we "succeed" even if there
# are errors. we just don't handle the errors)
exit 0