[CentOS] Virtual RPM howto?

Sat Oct 8 10:46:43 UTC 2011
Kenneth Porter <shiva at sewingwitch.com>

Can someone point me to a howto or an example of a virtual package?

I'm building Diaspora (the open source competitor to Facebook) and I 
figured it would be handy to gather all the prereqs into a virtual package.

I'm working from these instructions, which seemed to go fine on CentOS 6: