# grep pam /var/lib/portage/world
# tar jxf /usr/portage/distfiles/portage-2.0.51.19.tar.bz2 
# tar jxf /usr/portage/distfiles/portage-2.0.51.20.tar.bz2 
# portage-2.0.51.20/bin/emerge -n pam
Calculating dependencies ...done!
>>> Auto-cleaning packages ...

>>> No outdated packages were found on your system.


 Regenerating GNU info directory index...
 Processed 167 info files.
* IMPORTANT: 1 config files in /etc need updating.
 Type emerge --help config to learn how to update config files.

# grep pam /var/lib/portage/world
# portage-2.0.51.19/bin/emerge -n pam
Calculating dependencies ...done!
>>> Recording sys-libs/pam in "world" favorites file...
>>> Auto-cleaning packages ...

>>> No outdated packages were found on your system.


 GNU info directory index is up-to-date.
* IMPORTANT: 1 config files in /etc need updating.
 Type emerge --help config to learn how to update config files.

# grep pam /var/lib/portage/world
sys-libs/pam
#