The following file contains a nice description of the available USE flags:
/usr/portage/profiles/use.desc
Per-package USE flags can be defined in:
/etc/portage/package.use
The following file lists ‘explicitly’ installed packages:
/var/lib/portage/world
This file contains a lot of emerge messages that are sometimes missed when packages are installed:
/var/log/portage/elog/summary.log
equery (part of gentoolkit) is a tool that mildly resembles rpm:
gentoo ~ # equery files sysklogd [ Searching for packages matching sysklogd... ] * Contents of app-admin/sysklogd-1.4.2_pre20061230-r2: /etc /etc/conf.d /etc/conf.d/sysklogd ... /usr/share/man/man8/sysklogd.8.bz2 /usr/share/man/man8/syslogd-listfiles.8.bz2 /usr/share/man/man8/syslogd.8.bz2
gentoo ~ # equery belongs /etc/syslog.conf [ Searching for file(s) /etc/syslog.conf in *... ] app-admin/sysklogd-1.4.2_pre20061230-r2 (/etc/syslog.conf) gentoo ~ #
gentoo ~ # equery check sysklogd [ Checking app-admin/sysklogd-1.4.2_pre20061230-r2 ] * 31 out of 31 files good gentoo ~ #
These seem to pull data from the files in:
/var/db/pkg