#!/bin/bash

#Fail on errors!
set -e
set -u

#######################################################################
# /etc/cron.daily/backup - a script to backup one hd to               # 
# another on the same machine, using dump                             #
# (see the dump man page for details, and                             #
# http://envgen.nox.ac.uk/envgen/software/archives/000501.html#auto   #
#                                                                     #
# Written by MIT, 20/6/2002                                           #
# Modified by Dan Swan for Bio-Linux 2.0 17/3/2003                    #
# Updated for Bio-Linux 5 by Tim Booth 1/8/2008                       #
# Updated to perform Quarterly ETOH backups by Tony Travis 16/7/2009  #
#######################################################################

# Source configuration file
CONFIG=/etc/default/backup
if [ -r $CONFIG ]; then
    . $CONFIG
fi

# Where to backup
backup_destination=${DESTINATION:="/backups"}

# What to backup
backup_filesystems=(${FILESYSTEMS:="/ /home /var /usr"})

# Compression scheme.  For large drives bzip2 is probably too slow.
compression_mode=${COMPRESSION:="z"}

# Dump level can be set on command line or by today's date.
if [ -n "$*" ]; then
    level="$1"
else
    # get the date
    day=`date +%a`
    month=`date +%b`
    dom=`date +%d`

    # Quarterly Enhanced Towers of Hanoi
    if [ $day == "Sun" ]; then
        if [ $dom -lt 7 ]; then
            case $month in
            "Jan" | "Apr" | "Jul" | "Oct") level=0 ;;
            *) level=1 ;;
        esac
        elif [ $dom -lt 14 ]; then
            level=3
        elif [ $dom -lt 21 ]; then
            level=2
        elif [ $dom -lt 28 ]; then
            level=4
        elif [ $dom -le 31 ]; then
            level=3
        fi
    else
        case $day in
        "Mon") level=6 ;;
        "Tue") level=5 ;;
        "Wed") level=8 ;;
        "Thu") level=7 ;;
        "Fri") level=9 ;;
        "Sat") level=8 ;;
        esac
    fi
fi

# dirs to back up - used to be:
# backups=(hda1 hda2 hda5 hda6)
# But now I need to be a bit more sophisticated.
# List filesystems to back up and use mount to find where they are.
backups=()

for fs in "${backup_filesystems[@]}" ; do
    device=`mount | egrep "[^[:space:]]+ on $fs type ext[23]" | awk '{print $1}'`

    if [ "$device" != "" ]; then
	backups[${#backups[@]}]=$device
    fi
done

#DEBUG
#echo ${backups[@]} $level $compression_mode
#exit

# if backup drive is already mounted then try to unmount it first.              
# if this is in use the step will fail and exit                                 
/bin/mount | grep -q "/backups" && /bin/umount /backups 2>/dev/null

# mount necessary drive - must be listed
# in /etc/fstab in order to be mounted
/bin/mount "$backup_destination" 2>/dev/null || exit 0

# shut down MySQL during backup
/etc/init.d/mysql stop

# dump each directory, one at a time
for item in "${backups[@]}"; do
    basename=`basename $item`

    # sync or swim
    sync
    /sbin/dump -"$level" -"$compression_mode" -n -u -f "$backup_destination/$basename.bak.$level" "$item"
done

# start up MySQL after backup
/etc/init.d/mysql start

# umount drive
/bin/umount "$backup_destination"