#!/bin/bash
#       -*- Mode: sh  -*-

# check_disks_space.sh  -----------------------------------------------------

# Author        :  paissad (paissad_temp-spam@yahoo.fr)
# Created On    :  Fri Oct 29 13:10:16 CEST 2010
# Revision N°   :  3
# Status        :  Stable
# Description   :  Monitor or watch the disk space.
#                  Send an email if used disk space is >= 90% by default.
#                  Or if disk space is >= $Alert
# Depends       :
# Licence       :  GPLv3
#                __                          __
# .-----..---.-.|__|.-----..-----..---.-..--|  |
# |  _  ||  _  ||  ||__ --||__ --||  _  ||  _  |
# |   __||___._||__||_____||_____||___._||_____|
# |__|
# ---------------------------------------------------------------------------

# Example of use:
# mailTo="user@mail.com user2@localhost" Alert=95 ./check_disks_space.sh
# This will set threshold alert to 95% and send email to user@mail.com and
# user2@localhost

# Set an admin that will receive the mails (default: webmaster)
mailTo=${mailTo:-"$USER"}

# Set the threshold (default: 90%)
Alert=${Alert:-"90"}

# If 'Lock' is set to yes (default) ... the script avoids to send another
# email alert for the same partition. (May be useful when the script is used
# in cron jobs.
# The lock will be removed automatically if the partition retreive a normal
# disk space (not reach the alert !)
Lock=${Lock:-"yes"}
LockFile=${LockFile:-"$HOME/.check_disks_space.lock"}

# Send another mail 720 minutes (12 hours) after the previous one if the
# related disk is still in the lockfile !
# A null or negative value will deactivate this feature !
reminder=${reminder:-"720"} # in minutes

# Partitions and/or filesystems to exclude
# Must match correct regular expressions for grep
Exclude=${Exclude:-^Filesystem|/?tmpfs|/?cdrom[0-9]*|/?loop[0-9]*|/?dvd[0-9]*}

# ============================================================================
# You should not change anything below this line, except you know what you are
# doing
# ============================================================================

set -e
umask 0077

trap "if (($?)); then echo \"Error during the run of the script\";fi" EXIT

if [[ "$Lock" = "yes" ]]; then
    test -f $LockFile || { mkdir -p $(dirname $LockFile); touch $LockFile; }
fi

# $1 -> message
# $1 -> subject
# $3 -> admin(s) who receive the mail
function sendEmail(){
echo -e "$1" | mail -s "$2" "$3"
}

LANG=C df -HP \
| grep -vE "$Exclude" \
| awk '{ print $5 " " $1 }' \
| while read output
do
    usep=$(echo "$output" | awk '{ print $1}' | cut -d'%' -f1)
    partition=$(echo "$output" | awk '{ print $2 }')
    AlertSubject="Alert: Almost out of disk space for \"$partition ($usep%)\""
    AlertMessage="
-----------------------------------------------------------------------------
* The following partition has reached the threshold alert of $Alert%.
- Date             : $(date +"%a %d-%b-%Y %T (%Z)")
- Partition        : $partition
- Disk space used  : $usep%
- Machine hostname : $(hostname -f)
-----------------------------------------------------------------------------
"
    if [[ "$usep" -ge "$Alert" ]]; then
        echo >&2 -e "$AlertMessage"

        if [[ "$Lock" = "yes" ]]; then
            # Add partition to the lockfile if not present yet !
            grep -q -E -x "$partition" $LockFile 2>&1 > /dev/null \
            || { echo "$partition" >> "$LockFile"; \
            sendEmail "$AlertMessage" "$AlertSubject" "$mailTo"; }

            # Send a mail as reminder even if the disk has already been added
            # into the lockfile !
            if (($reminder > 0)) && [[ -n "$mailTo" ]]; then
                now=$(date +%s)
                lastMtime=$(date -r "$LockFile" +%s)
                ((diffTime=($now-$lastMtime)/60)) # in minutes !
                if (($diffTime >= $reminder)); then
                    grep -q -E -x "$partition" $LockFile 2>&1 > /dev/null && \
                    sendEmail "$AlertMessage" "$AlertSubject" "$mailTo" && \
                    touch "$LockFile"
                fi
            fi

        else
            # Send email in any case (because there is no lock file)
            sendEmail "$AlertMessage" "$AlertSubject" "$mailTo"
        fi
    else
        # Remove the partition from the$ lock file if it has retreived a
        # normal disk space
        if [[ -f "$LockFile" ]]; then
            if [ "$Lock" = "yes" ]; then
                partition_nn="$partition"  ## partition normal name
                partition=$(echo "$partition" | sed "s,\/,\\\/,g")
                grep -q -E -x "$partition_nn" "$LockFile" && \
                sed -i"_$$.bak" -e "/$partition/d" "$LockFile"
                rm -f "${LockFile}"_$$.bak
            fi
        fi
    fi
done