#!/bin/bash
#
#  This is a dump script from "info tar"
#  with lots of modifications.
#
#   Lots of help from info bash and from the web pages
#    http://www.student.nada.kth.se/~d96-jja/bash/bashtut.html
#    http://www.gnu.org/manual/bash/html_mono/bashref.html
#   Warning!   \ then space at the end of a line causes no end of problems
#
#  example recovery (done as root):
#
#    cd /backup
#    tar zxvf  dump0.tgz --listed-incremental dump0.inc home/bvds
#    tar zxvf  dump1.tgz --listed-incremental dump1.inc home/bvds
#    tar zxvf  dump2.tgz --listed-incremental dump2.inc home/bvds
#
#
#  Files to back up
#
files="/chez /etc /var /usr/local"
#
echo "  backup script $0 for files"
echo "    ${files}"
echo "  This is a version for at home use"
#
#  Zip drives are usually DOS formatted so
#  we have to be careful about using DOS-like names
#
#  Directory to put backups in
#
dir="/backup"
#
#  If the machine with the backup directory has
#  been rebooted, then the nfs volume becomes readonly.
#
mount $dir
#
#  file with number of backups performed on top of 
#  current level 0 dump.
#
countfile="${dir}/dump.cnt"
#
#
# Count number of dumps and find level
#
if [ $# -eq 0 ]; then
  if [ -e $countfile ]; then
    count=$(( $(cat $countfile) + 1 ))
    level=0
    j=$count
    until [ $j -eq 0 ]; do
      level=$(( $level+(j&1) ))
      j=$(( j>>1 ))
#      echo "in loop level is $level"
    done
  else
    echo "  Can't find file $countfile, exiting"
    exit 
  fi
else
 level=$1
 count=$(( (1<<$level) -1 ))
fi
#
# This is for testing purposes
#
#echo "count=$count level=$level"
#exit
#
# Move older copies to backup directory
# This moves all files at the present level and higher
#
if [ ! -d ${dir}/backback ]; then mkdir ${dir}/backback; fi
if [ ! -d ${dir}/back ]; then mkdir ${dir}/back; fi
#
i=$level
while [ -e ${dir}/dump${i}.tgz ]; do
  if [ -e ${dir}/back/dump${i}.tgz ]; then
    mv ${dir}/back/dump${i}.* ${dir}/backback
    echo "  Moving ${dir}/back/dump${i}.* to ${dir}/backback"
  fi
  mv ${dir}/dump${i}.* ${dir}/back
  echo "  Moving ${dir}/dump${i}.* to ${dir}/back"
  i=$(( i+1 ))
done
#
#
#  For dump levels higher than zero, find previous
#  snapshot file and copy it.
#
if [ $level -ne 0 ]; then
 datfile=${dir}/dump$(( $level -1 )).inc
 if [ -e $datfile ]; then
    cp $datfile ${dir}/dump${level}.inc
 else
   echo "Snapshot file $datfile doesn't exist, exiting"
   exit
 fi
fi
#
#  perform tar using snapshot file
#
#  turned off verbose -v 
#  The 2>&1 is supposed to redirect the STDERR to STDOUT
#
echo "  Starting level $level dump, this is dump number $count."
tar -z -c \
 -f $dir/dump${level}.tgz\
 --label="User dump on date $(date)"\
 --listed-incremental=$dir/dump${level}.inc\
 --exclude='/chez/carla/scratch'\
 --exclude='/chez/carla/brettshome.tar.gz'\
 ${files}  
#
#  save count in count file
#
echo $count > $countfile
#
# We don't want users to read the dump files
#
chmod 600 ${dir}/dump${level}.tgz
chmod 600 ${dir}/dump${level}.inc
#
umount $dir
#