Phusion Passenger users guide, Nginx version

Tweaking nginx.conf and more specifically, passenger pre-start directive

You can temporarily unload (disable) Phusion Passenger from Nginx, without uninstalling the Phusion Passenger files, so that Nginx behaves as if Phusion Passenger was never installed in the first place. This might be useful to you if, for example, you seem to be experiencing a problem caused by Phusion Passenger, but you want to make sure whether that’s actually the case, without having to go through the hassle of uninstalling Phusion Passenger completely. When disabled, Phusion Passenger will not occupy any memory or CPU or otherwise interfere with Nginx.

Full article: http://www.modrails.com/documentation/Users%20guide%20Ngi...