Equery

equery is a tool to make several common portage operations simpler. Among other operations, it can display package dependencies, metadata, and installed files.

Installation
Equery is available as part of the package in portage.

Usage
To see a list of all equery's capabilities, simply run it without arguments:

Each equery module can be run using either the full name or the indicated short name. For example, to get a list of what depends on a certain installed package, the depends module would be used.

Descriptions of other modules and additional command line flags can be found in the man page

External Resources

 * http://en.gentoo-wiki.com/wiki/Equery