#!/bin/bash
# ----------------------------------------------------------------------
# mikes handy rotating-filesystem-snapshot utility
# ----------------------------------------------------------------------
# RCS info: $Id: make_snapshot.sh,v 1.6 2002/04/06 04:20:00 mrubel Exp $
# ----------------------------------------------------------------------
# this needs to be a lot more general, but the basic idea is it makes
# rotating backup-snapshots of /home whenever called
# ----------------------------------------------------------------------

# ------------- system commands used by this script --------------------
ID=/usr/bin/id;
ECHO=/bin/echo;

MOUNT=/bin/mount;
RM=/bin/rm;
MV=/bin/mv;
CP=/bin/cp;
MKDIR=/bin/mkdir;
TOUCH=/bin/touch;

RSYNC=/usr/bin/rsync;


# ------------- file locations -----------------------------------------

MOUNT_DEVICE=/dev/hdb1;
SNAPSHOT_RW=/snapshots;
EXCLUDES=/home/craig/backup_exclude;
TOBACKUP=( root@big:/etc root@big:/home/craig root@big:/home/cajones root@big:/var/spool/mail ); # Bash array ${BACKUP[0]} ...


# ------------- the script itself --------------------------------------

# make sure we're running as root
if (( `$ID -u` != 0 )); then { $ECHO "Sorry, must be root.  Exiting..."; exit; } fi

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

# step 1: delete the oldest snapshot, if it exists:
echo "Deleting $SNAPSHOT_RW/hourly.3"
if [ -d $SNAPSHOT_RW/hourly.3 ] ; then			\
	$RM -rf $SNAPSHOT_RW/hourly.3 ;			\
fi ;

# rotating snapshots of /home (fixme: this should be more general)
# step 2: shift the middle snapshots(s) back by one, if they exist
if [ -d $SNAPSHOT_RW/hourly.2 ] ; then			\
	if [ ! -d $SNAPSHOT_RW/hourly.3 ] ; then \
		$MKDIR $SNAPSHOT_RW/hourly.3 ; \ 
	fi;	 
	echo "Moving $SNAPSHOT_RW/hourly.2 -> $SNAPSHOT_RW/hourly.3"; \
	$MV $SNAPSHOT_RW/hourly.2 $SNAPSHOT_RW/hourly.3 ;	\
fi;

if [ -d $SNAPSHOT_RW/hourly.1 ] ; then			\
	if [ ! -d $SNAPSHOT_RW/hourly.2 ] ; then \
		$MKDIR $SNAPSHOT_RW/hourly.2 ; \ 
	fi;	 
\
	echo "Moving $SNAPSHOT_RW/hourly.2 -> $SNAPSHOT_RW/hourly.3" ; \
	$MV $SNAPSHOT_RW/hourly.2 $SNAPSHOT_RW/hourly.3 ;	\
fi;

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

if [ ! -d $SNAPSHOT_RW/hourly.0 ] ; then			\
	$MKDIR  $SNAPSHOT_RW/hourly.0 ; \
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!
#
#   will backup all the dirs in the array $BACKUP
echo "Doing rsync"

for x in ${TOBACKUP[*]} ; do \

	BACKUPNAME=${x/:/}; \
	MACHINE=`echo $x | cut -s -d: -f1`; \

	echo "Making directory $SNAPSHOT_RW/hourly.0/$BACKUPNAME ..."; \
	$MKDIR -p $SNAPSHOT_RW/hourly.0/$BACKUPNAME; \

	$RSYNC								\
		-va --delete --delete-excluded				\
		-e ssh 							\
		--exclude-from="$EXCLUDES"				\
		${x}/ $SNAPSHOT_RW/hourly.0/$BACKUPNAME ;

	# step 5: update the mtime of hourly.0 to reflect the snapshot time
	$TOUCH $SNAPSHOT_RW/hourly.0/$BACKUPNAME ; \

done
echo "Done rsync"

# and thats it for home.

# now remount the RW snapshot mountpoint as readonly

#$MOUNT -o remount,ro $MOUNT_DEVICE $SNAPSHOT_RW ;
#if (( $? )); then
#{
#	$ECHO "snapshot: could not remount $SNAPSHOT_RW readonly";
#	exit;
#} fi;