Gentoo

Profile

A profile is a set of configuration files stored in /var/db/repos/gentoo/profiles that

specifies the default state of USE flags,
sets default values for most variables found in /etc/portage/make.conf,
defines a set of system packages, and
selects available package versions.

The currently used profile is pointed at by the (symbolic link?) /etc/portage/make.profile

A profile is selected at installation time, according to the intended use of the system.

A profile is set with eselect.

A list of profiles is produced with the command eselect profile list:

# eselect profile list
Available profile symlink targets:
  [1]   default/linux/amd64/17.1 (stable)
  [2]   default/linux/amd64/17.1/selinux (stable)
  [3]   default/linux/amd64/17.1/hardened (stable)
  [4]   default/linux/amd64/17.1/hardened/selinux (stable)
  [5]   default/linux/amd64/17.1/desktop (stable) *
  [6]   default/linux/amd64/17.1/desktop/gnome (stable)
  [7]   default/linux/amd64/17.1/desktop/gnome/systemd (stable)
  [8]   default/linux/amd64/17.1/desktop/gnome/systemd/merged-usr (stable)
  [9]   default/linux/amd64/17.1/desktop/plasma (stable)
  [10]  default/linux/amd64/17.1/desktop/plasma/systemd (stable)
  [11]  default/linux/amd64/17.1/desktop/plasma/systemd/merged-usr (stable)
  [12]  default/linux/amd64/17.1/desktop/systemd (stable)
  [13]  default/linux/amd64/17.1/desktop/systemd/merged-usr (stable)
  [14]  default/linux/amd64/17.1/developer (exp)
  [15]  default/linux/amd64/17.1/no-multilib (stable)
  [16]  default/linux/amd64/17.1/no-multilib/hardened (stable)
  [17]  default/linux/amd64/17.1/no-multilib/hardened/selinux (stable)
  [18]  default/linux/amd64/17.1/no-multilib/systemd (dev)
  [19]  default/linux/amd64/17.1/no-multilib/systemd/merged-usr (dev)
  [20]  default/linux/amd64/17.1/no-multilib/systemd/selinux (exp)
  [21]  default/linux/amd64/17.1/no-multilib/systemd/selinux/merged-usr (exp)
  [22]  default/linux/amd64/17.1/systemd (stable)
  [23]  default/linux/amd64/17.1/systemd/merged-usr (stable)
  [24]  default/linux/amd64/17.1/systemd/selinux (exp)
  [25]  default/linux/amd64/17.1/systemd/selinux/merged-usr (exp)
  [26]  default/linux/amd64/17.1/clang (exp)
  [27]  default/linux/amd64/17.1/systemd/clang (exp)
  [28]  default/linux/amd64/17.1/systemd/clang/merged-usr (exp)
  [29]  default/linux/amd64/17.0/x32 (dev)
  [30]  default/linux/amd64/17.0/x32/systemd (exp)
  [31]  default/linux/amd64/17.0/x32/systemd/merged-usr (exp)
  [32]  default/linux/amd64/17.0/musl (dev)
  [33]  default/linux/amd64/17.0/musl/clang (exp)
  [34]  default/linux/amd64/17.0/musl/hardened (exp)
  [35]  default/linux/amd64/17.0/musl/hardened/selinux (exp)

eselect

eselect is a utility that allows for a common management interface for system administration

Without arguments, eselect lists all currently installed modules.

Ebuild repositories

An ebuild repository provides packages which can be installed on a Gentoo system.

The most important ebuild repository is the Gentoo ebuild directory which is hosted at gitweb.gentoo.org.

The locally synchronized copy of the Gentoo ebuild directory is located in /var/db/repos/gentoo.

Other well known repositories include

GURU
repos.gentoo.org
gpo.zugaina.org (third-party list of ebuild repositories)

An ebuild repository stores ebuild files which contain the instructions on how to build and install a package.

Local mirrors of ebuild repositories can be synchronized with one of the following commands

emaint sync --auto
emaint sync --repo my-private-repo
emaint sync --allrepos

News items

News items contain messages for users. These are synchronized(?) along with the synchronization of the Gentoo ebuild repository.

News items can be shown and read with

eselect news list
eselect news read

Such news items seem to be relatively rare (14 items in 4 years):

# eselect news list
News items:
  [1]      2018-08-07  Migration required for OpenSSH with LDAP
  [2]      2019-05-23  Change of ACCEPT_LICENSE default
  [3]      2020-06-23  sys-libs/pam-1.4.0 upgrade
  [4]      2021-01-30  New OpenRC Display Manager Initializer Scripts
  [5]      2021-07-20  Perl 5.34 upgrade now stable
  [6]      2021-09-29  Possible failure to preserve libraries
  [7]      2021-10-08  OpenSSH RSA SHA-1 signatures
  [8]      2021-10-18  migrating from glibc[crypt] to libxcrypt in stable
  [9]      2021-10-24  netifrc DHCP client
  [10]     2022-03-30  Qt 5.15.3 version bump with binary path changes
  [11]     2022-04-19  Migration to sys-apps/systemd-utils
  [12]     2022-11-21  systemd-tmpfiles --clean enabled by default
  [13]     2022-12-27  Introduction of app-alternatives ebuilds
  [14]     2023-05-11  OpenSSH directory configuration changes

Kernel configuration

There are two ways to configure the Kernel:

automatic (genkernel)
manual

genkernel is a relatively dumb script and leaves several things to the user, such as WIFI or 3D video acceleration (but see also the -menuconfig option of genkernel).

As an alternative to Kernel configuration, there is also the Distribution Kernel.

Gentoo Linux Enhancement Proposal (GLEP)

A GLEP is a document that provides information or describes a new feature to the Gentoo community.

GLEPs are very similar to Python's PEPs.

Interesting GLEPs include:

23: Handling of ACCEPT_LICENSE (See also /etc/portage/make.conf)

TODO

/etc/env.d/

/var/db/repos/gentoo/profiles/use.desc describes USE flags.