#!/bin/sh 

RSYNC=/usr/bin/rsync
SSH=/usr/bin/ssh
KEY=/home/user/.ssh/rsync-key
RUSER=user
RHOST=production-server
RPATH=/production-directory/
LPATH=/backup-directory/

$RSYNC -a --delete -e "$SSH -i $KEY" $RUSER@$RHOST:$RPATH $LPATH