eZ Deploy is an automatic deploy system based on rsync shell script. It allows to deploy ez application from dev environment to production environment via rsync system. Yuo can configure wich files to exclude and different environment to deploy.

It's a shell command and to use it you need to have installed on your server and on your client rsync (http://samba.anu.edu.au/rsync/)

You can also make a site offline or online executing a shell scripting and you can customizing a template for your landing page message while site is down.