rsync --link-dest --rsync-path など

覚書

HOST=192.168.1.172
CMD=/usr/local/bin/rsync
OLDEST=`date --date '7 days ago' +%Y%m%d`
LATEST=`date --date '1 days ago' +%Y%m%d`

rm -fr $HOST/$OLDEST
mv $HOST/current $HOST/$LATEST

$CMD -narzv --delete \
--link-dest="../$LATEST/" \
--rsync-path="sudo $CMD" \
--exclude-from=excludes.txt \
/ backup@$HOST:$HOST/current/