ZFS snapshot backup

backupdaily.sh

#!/usr/bin/bash
for fs in dir1 dir2 dir3 ; do
        srcfs="tank/$fs"
        dstfs="backup/$fs"
        oldsnap=`zfs list -H -r -t snapshot $dstfs |cut -f1 | grep '0000$' | sort | tail -1 | sed -e 's/.*@//'`
        newsnap=`zfs list -H -r -t snapshot $srcfs |cut -f1 | grep '0000$' | sort | tail -1 | sed -e 's/.*@//'`
        
        if [ x$newsnap != x ] ; then
                if [ x$oldsnap != x ] ; then 
                        echo "$fs: from fat/san/$fs@$oldsnap to $newsnap if needed..."
                        if [ $oldsnap != $newsnap ] ; then
                                zfs send -v -i $oldsnap fat/san/$fs@$newsnap | mbuffer -b 1  | zfs receive -d backup
                        fi
                fi
        fi
done
echo Done.