emerge world
emerge: superuser access would be required.

mustapha@damas:~$ sudo emerge world
Calculating world dependencies... done!
>>> Auto-cleaning packages...

>>> No outdated packages were found on your system.
 * GNU info directory index is up-to-date.
 * IMPORTANT: 22 config files in '/etc' need updating.
 * Type emerge --help config to learn how to update config files.