#!/bin/sh

## Snapshot zfs data directories and keep one
## week of snapshots.
## spk - 2012-09-17 - v1.0 - Basic script 
## spk - 2012-09-17 - v1.1 - Added test for log file

# Set up some variables
LOG=/var/log/data_snap.log
DATE=/usr/bin/date
ECHO=/usr/bin/echo

# Set up the log file
if test ! -f $LOG; then
	touch $LOG
else
	continue
fi

# Let people know we're starting...
$ECHO "*************************************************" >> $LOG
$ECHO "`$DATE` - Starting snapshot process" >> $LOG

# Check if there is an existing 7-day old snapshot
zfs list -H -t snapshot|grep 7daysago > /dev/null
if test $? -eq 0; then
	$ECHO "`$DATE` - Deleting 7 day old snapshot" >> $LOG
#	for snap in `zfs list -H -o name -t snapshot|grep 7daysago`; do echo zfs destroy $snap >> $LOG && zfs destroy $snap; done
	zfs destroy -r data@7daysago
		if test $? -ne 0; then 
			$ECHO "`$DATE` - Problem renaming 7 day old snapshot, exiting!" >> $LOG
			exit 1
		else
			continue
		fi	
else
	$ECHO "`$DATE` - No 7daysago snapshot - not renaming" >> $LOG
fi

## Check snapshots exist and rename them if they do...
# Rename the 6 day old snapshot to 7 days old..
zfs list -H -t snapshot|grep 6daysago > /dev/null
if test $? -eq 0; then
        $ECHO "`$DATE` - Renaming 6 day old snapshot" >> $LOG
        zfs rename -r data@6daysago data@7daysago
                if test $? -ne 0; then
                        $ECHO "`$DATE` - Problem renaming 6 day old snapshot, exiting!" >> $LOG
                        exit 1
                else
                        continue
                fi
else
        $ECHO "`$DATE` - No 6daysago snapshot - not renaming" >> $LOG
fi

# Rename the 5 day old snapshot to 6 days old..
zfs list -H -t snapshot|grep 5daysago > /dev/null
if test $? -eq 0; then
        $ECHO "`$DATE` - Renaming 5 day old snapshot" >> $LOG
        zfs rename -r data@5daysago data@6daysago
                if test $? -ne 0; then
                        $ECHO "`$DATE` - Problem renaming 5 day old snapshot, exiting!" >> $LOG
                        exit 1
                else
                        continue
                fi
else   
        $ECHO "`$DATE` - No 5daysago snapshot - not renaming" >> $LOG
fi

# Rename the 4 day old snapshot to 5 days old..
zfs list -H -t snapshot|grep 4daysago > /dev/null
if test $? -eq 0; then
        $ECHO "`$DATE` - Renaming 4 day old snapshot" >> $LOG
        zfs rename -r data@4daysago data@5daysago
                if test $? -ne 0; then
                        $ECHO "`$DATE` - Problem renaming 4 day old snapshot, exiting!" >> $LOG
                        exit 1
                else
                        continue
                fi
else   
        $ECHO "`$DATE` - No 4daysago snapshot - not renaming" >> $LOG
fi

# Rename the 3 day old snapshot to 4 days old..
zfs list -H -t snapshot|grep 3daysago > /dev/null
if test $? -eq 0; then
        $ECHO "`$DATE` - Renaming 4 day old snapshot" >> $LOG
        zfs rename -r data@3daysago data@4daysago
                if test $? -ne 0; then
                        $ECHO "`$DATE` - Problem renaming 3 day old snapshot, exiting!" >> $LOG
                        exit 1
                else
                        continue
                fi
else   
        $ECHO "`$DATE` - No 3daysago snapshot - not renaming" >> $LOG
fi

# Rename the 2 day old snapshot to 3 days old..
zfs list -H -t snapshot|grep 2daysago > /dev/null
if test $? -eq 0; then
        $ECHO "`$DATE` - Renaming 2 day old snapshot" >> $LOG
        zfs rename -r data@2daysago data@3daysago
                if test $? -ne 0; then
                        $ECHO "`$DATE` - Problem renaming 2 day old snapshot, exiting!" >> $LOG
                        exit 1
                else
                        continue
                fi
else   
        $ECHO "`$DATE` - No 2daysago snapshot - not renaming" >> $LOG
fi

# Rename yesterday's snapshot to 2 days old..
zfs list -H -t snapshot|grep yesterday > /dev/null
if test $? -eq 0; then
        $ECHO "`$DATE` - Renaming yesterday's snapshot" >> $LOG
        zfs rename -r data@yesterday data@2daysago
                if test $? -ne 0; then
                        $ECHO "`$DATE` - Problem renaming yesterday's snapshot, exiting!" >> $LOG
                        exit 1
                else
                        continue
                fi
else   
        $ECHO "`$DATE` - No snapshot from yesterday - not renaming" >> $LOG
fi

# Rename today's snapshot to yesterday's..
zfs list -H -t snapshot|grep today > /dev/null
if test $? -eq 0; then
        $ECHO "`$DATE` - Renaming today's snapshot" >> $LOG
        zfs rename -r data@today data@yesterday
                if test $? -ne 0; then
                        $ECHO "`$DATE` - Problem renaming today's snapshot, exiting!" >> $LOG
                        exit 1
                else
                        continue
                fi
else   
        $ECHO "`$DATE` - No snapshot from today - not renaming" >> $LOG
fi

## Finally, we take a new snapshot...
zfs snapshot -r data@today
if test $? -eq 0; then
	$ECHO "`$DATE` - New Snapshot taken successfully" >> $LOG
else
	$ECHO "`$DATE` - Snapshot failed!" >> $LOG
	exit 2
fi

# Let's finish the script..
$ECHO "`$DATE` - Snapshot creation finished!" >> $LOG
$ECHO "****************************************************" >> $LOG