Eix

eix is a set of utilities for searching and diffing your local portage-tree and overlays using a binary cache.

It is made to be more efficient and flexible than emerge's search functionality, comes with colorized output and helps you to more easily find the package information you need.

Installation
Install :

after the installation has finished, it is important to update the cache and index all packages on the system.

Updating the cache
Running following command will update the local eix cache and index all packages on the system.

To spare out some typing work, run following command:

which is shorthand to run these commands sequentially:

Adding overlays to the cache
To search not only in the portage tree but all the overlays, add overlays to the cache

Searching for packages
Examples:

Simple search
To find package names containing kernel keyword:

Searching for installed packages
Searching for installed -I packages:

Searching in package descriptions
Searching in package descriptions -S, printing out results in a compact -c list:

Searching in package categories
Searching for certain category -C print out a compact -c results list:

Searching for installed obsolete packages
Searching for obsolete packages on the system:

External resources

 * Community Gentoo Wiki article