backup.sh

#!/bin/sh
# rotating snapshotted backup

src=/my/stuff
dest=/var/backup
today=`date +%a`
yesterday=`date -d yesterday +%a`

mkdir -p $dest/$yesterday # in case it doesn't exist yet
rm -rf $dest/$today # I think this might be necessary -- not sure
cp -al $dest/$yesterday $dest/$today
rsync -ra --delete $src/* $dest/$today