warn_disk_usage.sh

#!/bin/bash

#    This script is used to send an e-mail notification if a certain partition
#    is running out of space. The message will be delivered if either the disk
#    usage in partition $PART is bigger than $MAXPERC or the amount of free
#    space is smaller than $MINFREE.
#
#    Copyright (C) 2013, Henning Hollermann, laclaro@mail.com
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation, either version 3 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program.  If not, see <http://www.gnu.org/licenses/>.

# percentage of disk usage, where mail should be sent
MAXPERC=95 # percent
# minimum free space, below e-mail should be sent
MINFREE=15 # GB
# mail destination
MAIL_DESTINATION=admin@domain.com
# surveilled partition
PART=partition_name

# free space in bytes
FREE=`df |grep $PART | awk '{ print $4 }'`

# percentage of disk space used and df-info line
if [ -x /usr/bin/pydf ]; then
  USEPERC=`pydf --bw |grep $PART | awk '{ printf("%.0f",$5) }'`
  DF_LINE=`pydf --bw|awk '
    BEGIN { print "  Disk space" };
    /'$PART'/{print "  "$7 "\t" $3 "/" $2 " (" $5 "%)\tfree: "$4 "\n  " $6};
    END { print ""}'`
else
  USEPERC=`df -h |grep $PART | awk '{ print $5 }' | cut -d'%' -f1`
  DF_LINE=`df -h|awk '
     BEGIN { print "  Disk space" };
     /Size|'$PART'/{print "  "$2 "\t" $3 "\t" $4 "\t" $5 "\t" $6};
     END { print ""}'`
fi
echo $FREE $(($MINFREE*1000000))
# if conditions met, send e-mail
if [ $USEPERC -gt $MAXPERC -o $FREE -lt $(($MINFREE*1000000)) ]; then
  echo -e "
Hello,\n
this message was automatically created by $0.
Partition $PART is running out of space (${USEPERC}% used).\n
$DF_LINE\n
You may clear the trash bin to free some space.\n
`cat /tmp/motd-trashes`\n
Best wishes, the administrator
" | mail -s "$PART is running out of space" $MAIL_DESTINATION

fi