World set (Portage)

The world file, by default located in /var/lib/portage/world, contains the set of package atoms that the user has directly asked to have installed.

It is the world file, together with the profile, /etc/make.conf and /etc/portage settings that defines which software is installed on the system. Whenever a user triggers a software installation (through emerge ) this software package name is registered in the world file. Later, when a world update is requested (through emerge -uDN world or similar) Portage will use this file as the base for its update calculations.