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This document is a WORK IN PROGRESS.
This is just a quick personal cheat sheet: treat its contents with caution!

Gentoo system

Reference(s)

Table of contents

Important portage files

Reference(s)

WIP

  • /etc/env.d - d: files containing global variables for the apps in their name

  • /etc/portage/make.conf - f: global settings (USE flags, compiler options...)

  • /etc/portage/make.profile - d: portage profile symlink directory

  • /etc/portage/package.accept_keywords - d: keyword individual packages

  • /etc/portage/package.license - Accepted licenses
  • /etc/portage/package.use - d: USE flags of individual packages
  • /etc/portage/package.mask -

  • /etc/portage/package.unmask -

  • /usr/share/portage/config/make.conf - f: portage config file having precedence

  • /usr/share/portage/config/make.globals - f: portage default config file

  • /usr/share/portage/config/make.defaults

  • /var/lib/portage/world - d: list of explicitly installed package atoms

  • /var/db/pkg - d: contains a files set about the installation of every package

  • /var/lib/portage/world - f: the selected packages set contains the user selected @world packages

OpenRC and init scripts

Reference(s)

OpenRC is a dependency based init system that maintains compatibility with the system provided init program.

  • Print the status of every services: 

    $ rc-status --all

  • Print the level of every services: 

    $ rc-status --all

TODO

gentoolkit

Reference(s)

USE flags

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A USE flag is a variable that embodies support and dependency information for a certain concept. If you add a USE flag (e.g. kde), Portage will compile the related packages accordingly (e.g. with kde support). On the contrary you can specify to remove a USE flag (e.g. -kde) to not support it. Of course this also alters the dependency information for a package.

Check USE flags of the system: 

$ emerge --info | grep ^USE # list currently active USE settings
$ less /usr/portage/profiles/use.desc # full desc. on the available USE flags

Check USE flags of a specific package: 

$ emerge -pv pkg_name # check, among other things, available use flags of a pkg
or
$ equery uses pkg_name

Global USE flags

See USE: Use flags system wide.

Local USE flags

One can change local USE flags in /etc/portage/package.use

E.g. enabling the bluray USE flag for vlc, and disabling bzip2 for php: 

# echo "media-video/vlc bluray" >> /etc/portage/package.use/vlc
# echo "dev-lang/php -bzip2" >> /etc/portage/package.use/php

After modifying a local (specific to a package) USE flag: update the related package 

# emerge -a specific-package-to-update

USE flags common commands

$ man euse # gather more information on euse by reading its manual page

$ euse -i png # obtain descriptions and usage of png USE flag

$ euse -i | grep png # obtain a description of png USE flag

$ equery hasuse png # show what packages have png USE flag

$ eix --installed-with-use png # show what packages are built with png USE flag

$ equery uses package_name # show what USE flags are available for a package

KEY words

Reference(s)

KEYWORDS variable informs in which architectures the package is stable or still in testing phase.

Examples of possible key words values: alpha, amd64, arm, arm64 ...

The prefix ~ (tilde character) placed in front of an architecture means that it is in a "testing phase" and is not ready for production usage.

Global KEY word

See ACCEPT_KEYWORDS: stable vs testing system wide

Local KEY word

If your system is an amd64 based architecture and you just want the last version of a specific package, not available on the stable branch (e.g. with the rust package): 

# echo "dev-lang/rust ~amd64" >> /etc/portage/package.accept_keywords

Licenses

Reference(s)

Since 2019-05-23 (https://www.gentoo.org/support/news-items/2019-05-23-accept_license.html) the default accepted license has changed, now only free software and documentation will be installable.

Global license

See ACCEPT_LICENSE: license system wide

Local license

It also can be specified on a per package basis in /etc/portage/package.license.

For example, to allow the app-arch/unrar and sys-kernel/linux-firmware packages to be installed, the following lines would have to be added to /etc/portage/package.license: 

# vi /etc/portage/package.license
    > ...
    > app-arch/unrar unRAR
    > sys-kernel/linux-firmware @BINARY-REDISTRIBUTABLE
    > ...

Other /etc/portage/package.license examples: 

# vi /etc/portage/package.license
    > ...
    > # Accepting google-chrome license for www-client/google-chrome for version equal or greater
    > # than 42.0.2311.90_p1:
    > >=www-client/google-chrome-42.0.2311.90_p1 google-chrome
    >
    > # Accepting google-chrome license for any version of www-client/google-chrome:
    > www-client/google-chrome google-chrome
    >
    > # Accepting google-chrome license for every www-client package at any version:
    > www-client/* google-chrome
    >
    > # Accepting google-chrome license for every package at any version:
    > */* google-chrome
    >
    > # Accepting every license for every package at any version (not a good idea):
    > */*  *

Portage features

Full overview of portage features : 

$ man make.conf

Portage features includes distcc, ccache, prebuilt-packages...

make.conf

Reference(s)

USE: Use flags system wide

One can change global USE flags in /etc/portage/make.conf

E.g. enabling ldap USE flag, and disabling kde and gnome all system wild: 

# euse -D kde gnome
# euse -E ldap
$ grep USE /etc/portage/make.conf # check that the use flags have been append:
    > USE="... -kde -gnome ldap"

Warning

After modifying the USE variable in your make.conf, don't forget to update the system using the following command so the changes take effect: # emerge --ask --changed-use --deep @world

ACCEPT_KEYWORDS: stable vs testing system wide

If your system is an amd64 based architecture and you want all your packages as bleeding edge as possible: 

# vi /etc/portage/make.conf
    > ...
    > ACCEPT_KEYWORDS="~amd64"
    > ...

Warning

After modifying the ACCEPT_KEYWORDS variable in your make.conf, don't forget to do a full update of your system for the changes to take effect.

ACCEPT_LICENSE: license system wide

The ACCEPT_LICENSE variable can be modified in /etc/portage/make.conf for a global impact, e.g.: 

# sudo vi /etc/portage/make.conf
    > ...
    > ACCEPT_LICENSE="* -@EULA"  # any license exept EULA
    > ...

CFLAGS: Optimize CPU

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TODO

Install and run app-portage/cpuid2cpuflags

$ sudo -i
# echo "*/* $(cpuid2cpuflags)" >> /etc/portage/package.use/00cpuflags

CCACHE: Optimize builds

Reference(s)

TODO

The ccache directory might involve some space to be useful (the default configuration limit its space to 100 Go)...

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