#!/bin/bash

# full and incremental backup script
# created 07 February 2000
# Based on a script by Daniel O'Callaghan <danny@freebsd.org>
# and modified by Gerhard Mourani <gmourani@videotron.ca>
# and modified 19 December 2009 by Michael Burns <mike@michaelburns.name>

PATH=/usr/bin:/bin


#################################################
#################################################
# Change the follwing variables below to fit your computer/backup

# name of this computer
COMPUTER=`hostname`			# or fixed to your liking

# directoris to backup -- one per line
DIRECTORIES="/home/me
             /sharedocs"

#####
# The following directories are used to store the backups and
# various logs. Make sure you create these directories by hand
# before running this script!!!
#####

# where to store the backups
BACKUPROOT=/backup
BACKUPDIR=${BACKUPROOT}/me/nightly

# where to store time of full backup
TIMEDIR=${BACKUPDIR}/last-full  

# where to store the log files
LOGDIR=${BACKUPDIR}/logs

# name and locaction of tar
TAR=/bin/tar


#################################################
#################################################
# You should not have to change anything below here

DOW=`date +%a`              		# Day of the week e.g. Mon
NDOW=`date +%u`                         # Day of the week number e.g. 1 = Mon
DOM=`date +%d`              		# Date of the Month e.g. 27
MON=`date +%m`				# Month e.g. 01 = January
DM=`date +%d%b`                   	# Date and Month e.g. 27Sep

forcefull=0				# force a full backup
forceincremental=0			# force an incremental backup


#
# On the 1st of the month and the last day of the year, 12/31, a
# permanent full backup is made.
#
# Every Sunday a full backup is made. Last Sunday's backup will be
# overwritten.
#
# The rest of the time an incremental backup is made. Each incremental
# backup overwrites last weeks incremental backup of the same name.
#
# If NEWER = "", then tar backs up all files in the directories.
# Otherwise, it backs up all files newer than the NEWER date. NEWER
# gets it date from the file written every Sunday. (A full backup
# does not update the "last-full" file.)
#


# Allow a "forced" monthly full backup (specify "full" on the command line)
if [ ! -z $1 ] && [ $1 = "full" ]; then
  forcefull=1
  echo Param = full -- setting forcefull to 1
fi

# Force a full backup for 12/31 -- year end
if [ $DOM = "31" ] && [ $MON = "12" ]; then
  forcefull=1
  echo Date is 12/31 -- setting forcefull to 1
fi 

# Monthly full backup
if [ $DOM = "01" -o $forcefull -eq 1 ]; then
  NEWER=""
  echo "Performing monthly full backup ..." > $LOGDIR/$COMPUTER-$DM.log
  echo "" >> $LOGDIR/$COMPUTER-$DM.log
  $TAR --gzip $NEWER -chvf $BACKUPDIR/$COMPUTER-$DM.tar.gz $DIRECTORIES >> $LOGDIR/$COMPUTER-$DM.log 2> $LOGDIR/$COMPUTER-$DM.error

  # force an incremental to prevent two full backups from occurring
  echo "Performed full backup -- setting forceincremental to 1" > $LOGDIR/$COMPUTER-$DM.log
  forceincremental=1
fi

# Weekly full backup
if [ $NDOW = "7" -a $forceincremental -eq 0 ]; then
  NEWER=""
  NOW=`date +%d-%b`

  echo "Performing weekly full backup ..." > $LOGDIR/$COMPUTER-$NDOW-$DOW.log
  echo "" >> $LOGDIR/$COMPUTER-$NDOW-$DOW.log

  # Update full backup date
  echo $NOW > $TIMEDIR/$COMPUTER-full-date
  $TAR --gzip $NEWER -chvf $BACKUPDIR/$COMPUTER-$NDOW-$DOW.tar.gz $DIRECTORIES >> $LOGDIR/$COMPUTER-$NDOW-$DOW.log 2> $LOGDIR/$COMPUTER-$NDOW-$DOW.error

# Make incremental backup - overwrite last weeks
else
  # Get date of last full backup
  NEWER="--newer `cat $TIMEDIR/$COMPUTER-full-date`"

  echo "Performing daily incremental backup (newer = ${NEWER}) ..." > $LOGDIR/$COMPUTER-$NDOW-$DOW.log
  echo "" >> $LOGDIR/$COMPUTER-$NDOW-$DOW.log

  $TAR --gzip $NEWER -chvf $BACKUPDIR/$COMPUTER-$NDOW-$DOW.tar.gz $DIRECTORIES >> $LOGDIR/$COMPUTER-$NDOW-$DOW.log 2> $LOGDIR/$COMPUTER-$NDOW-$DOW.error
fi