Make sure that both rsync and ssh are in the path of the local and remote
user
Snip from a script
....
rsync="/usr/local/bin/rsync --force --delete -rzle /usr/local/bin/ssh"
$rsync /local/path/to/mirror/ remote_user_name@target.yale.edu:/target
....
It is a fussy program....and trailing slashes have weird effects which you
have to figure out from the directions and just testing. There's also an
rsync daemon which I've never used.