make_snapshot.sh

#!/bin/bash
# ----------------------------------------------------------------------
# mikes handy rotating-filesystem-snapshot utility
# ----------------------------------------------------------------------
# this needs to be a lot more general, but the basic idea is it makes
# rotating backup-snapshots of /home whenever called
# ----------------------------------------------------------------------

export DIRNAME=/usr/bin/dirname;
export REALPATH=/usr/bin/realpath;

unset PATH	# suggestion from H. Milz: avoid accidental use of $PATH
CWD=`$DIRNAME $($REALPATH $0)`
source $CWD/backup.config;

# ------------- the script itself --------------------------------------
$TOUCH $DIAGNOSTICLOG;
$ECHO "*****************************************************************************" >> $DIAGNOSTICLOG;
$ECHO "$($DATE) - SNAPSHOT CREATION STARTED" >> $DIAGNOSTICLOG;

# make sure we're running as root
if [ `$ID -u` != "0" ]; then { $ECHO "$($DATE) - This script must be run as root" >> $DIAGNOSTICLOG; exit 1; } fi

# attempt to remount the RW mount point as RW; else abort
$MOUNT -o remount,rw $MOUNT_DEVICE $SNAPSHOT_RW ;
if (( $? )); then
{
  $ECHO "$($DATE) - SNAPSHOT: could not remount $SNAPSHOT_RW readwrite" >> $DIAGNOSTICLOG;
  exit;
}
fi;

# rotating snapshots

# step 1: delete the oldest snapshot, if it exists:
if [ -d $SNAPSHOT_RW/daily.6 ] ; then
  $RM -rf $SNAPSHOT_RW/daily.6 ;
fi ;

 step 2: shift the middle snapshots(s) back by one, if they exist
if [ -d $SNAPSHOT_RW/daily.5 ] ; then
  $MV $SNAPSHOT_RW/daily.5 $SNAPSHOT_RW/daily.6 ;
fi;
if [ -d $SNAPSHOT_RW/daily.4 ] ; then
  $MV $SNAPSHOT_RW/daily.4 $SNAPSHOT_RW/daily.5 ;
fi;
if [ -d $SNAPSHOT_RW/daily.3 ] ; then
  $MV $SNAPSHOT_RW/daily.3 $SNAPSHOT_RW/daily.4 ;
fi;
if [ -d $SNAPSHOT_RW/daily.2 ] ; then
  $MV $SNAPSHOT_RW/daily.2 $SNAPSHOT_RW/daily.3 ;
fi;
if [ -d $SNAPSHOT_RW/daily.1 ] ; then
  $MV $SNAPSHOT_RW/daily.1 $SNAPSHOT_RW/daily.2
fi;

# step 3: make a hard-link-only (except for dirs) copy of the latest snapshot,
# if that exists
if [ -d $SNAPSHOT_RW/daily.0 ] ; then
  $CP -al $SNAPSHOT_RW/daily.0 $SNAPSHOT_RW/daily.1 ;
fi;

# step 4: rsync from the system into the latest snapshot (notice that
# rsync behaves like cp --remove-destination by default, so the destination
# is unlinked first.  If it were not so, this would copy over the other
# snapshot(s) too!
$RM -f /Installed_Packages
/usr/bin/dpkg --get-selections > /Installed_Packages
$RSYNC -vha --delete --delete-excluded --exclude-from="$EXCLUDES" --include-from="$INCLUDES" $SNAPSHOT_RW/daily.0 --log-file=$SNAPSHOT_RW/$LOGFILE;

$MV $SNAPSHOT_RW/$LOGFILE $SNAPSHOT_RW/daily.0/

# step 5: update the mtime of daily.0 to reflect the snapshot time
$TOUCH $SNAPSHOT_RW/daily.0 -t $DATESTAMP;

$RM $SNAPSHOT_RW/rsync.log.*
# and thats it.

# now remount the RW snapshot mountpoint as readonly

$MOUNT -o remount,ro $MOUNT_DEVICE $SNAPSHOT_RW ;
if (( $? )); then
{
  $ECHO "$($DATE) - SNAPSHOT: could not remount $SNAPSHOT_RW readonly" >> $DIAGNOSTICLOG;
  exit;
}
fi;
$TAIL $SNAPSHOT_RW/daily.0/$LOGFILE -n 2 | $SED -e 's/.*\]//' >> $DIAGNOSTICLOG;
$ECHO "$($DATE) - SNAPSHOT CREATION FINISHED, GOING BACK TO SLEEP" >> $DIAGNOSTICLOG;
$SUSPEND;