Selected-packages set (Portage)

The selected-packages set Article description::contains the user-selected "world" packages that are listed in the file.

Listing the selected-packages set
eix can be used to list the selected-packages set:

Emerge a package without adding it to the world file
In order to avoid problems in dependency resolution when updating the system, the file should contain as few dependencies as possible. So use the   option for emerging dependencies.

Checking the world file
The command can be used to see if any problems exist in the world file:

Keeping the world file clean
Dependencies already listed in this file can be found using the command and be collected in a file say :

Entries collected in can be cross-checked using the   option:

The option will remove these entries without unmerging them.

In case indicates some needed or wanted package would be unmerged, those can be re-added using the  option. See the next section for details.

Adding an atom without recompilation
To add a package to the selected-packages set without recompiling the package:

It will add the atom to the file without compiling it again.

External resources

 * https://forums.gentoo.org/viewtopic-t-1075276.html - Cleaning the world file (wiki) - check the script.