Gentoo Cheat Sheet 02.09.17

Package management
Sync methods

Sync all repositories that are set to auto-sync including the Gentoo ebuild repository:
root #emaint -a sync

Sync the Gentoo ebuild repository using the mirrors by obtaining a snapshot that is (at most) a day old:
root #emerge-webrsync

Sync custom package repository and the Gentoo ebuild repository using eix:
root #eix-sync

app-portage/eix can be installed by issuing:
root #emerge -a eix

Gather more information on eix by reading its manual:
user $man eix
Package installation and removal

In the following tips www-client/firefox will be used as an example, substitute Firefox with the package of interest to perform the actions on another package.

List what packages would be installed without installing them:
root #emerge -pv www-client/firefox

Install a specific version of a package (Use '\=' if your shell attaches meaning to '='):
root #emerge =www-client/firefox-24.8.0

Install a package but excluding it from the world file:
root #emerge --oneshot www-client/firefox

or
root #emerge -1 www-client/firefox

Remove a package that no other packages depend on:
root #emerge -cav www-client/firefox

Remove a package even if it is needed by other packages:
root #emerge -C www-client/firefox
Warning
Use with caution. This can break software. Best if used to temporarily remove to satisfy a hard block.

Remove packages no longer needed:
root #emerge -av --depclean

As a safety measure, depclean will not remove any packages unless all required dependencies have been resolved. As a consequence of this, it often becomes necessary to run:
root #emerge --update --newuse --deep @world

Avoid unnecessary rebuilds when USE flags only get added to or dropped from the repository:
root #emerge --update --changed-use --deep @world
Package upgrades

Upgrade all installed packages, dependencies, and deep dependencies that are outdated or have USE flag changes (avoiding unnecessary rebuilds when USE changes have no impact):
root #emerge -uDU --keep-going --with-bdeps=y @world
Package troubleshooting

Check for and rebuild missing libraries:
root #revdep-rebuild -v

equery is part of app-portage/gentoolkit. You can obtain it by issuing this command:
root #emerge -a gentoolkit

Tell which installed package provides a command using equery:
user $equery b `which vim`

Tell which packages depend on a specific package (cat/pkg in the example) using equery:
user $equery d www-client/firefox

Get information about a package using eix:
root #eix www-client/firefox
Portage enhancements

A graphical user interface to use with the Portage tree:
root #porthole

Manage configuration changes after an emerge completes:
root #dispatch-conf
After installations or updates

Rebuilds packages that depend on an recently updated library:
root #revdep-rebuild

After updating perl-core packages:
root #perl-cleaner --all

For haskell packages:
root #haskell-updater

For python packages:
root #python-updater
USE flags

Obtain descriptions and usage of the USE flag X using euse:
user $euse -i X

Gather more information on euse by reading its manual page:
user $man euse

Obtain a description of the png USE flag:
user $euse -i | grep png

Show what packages have the mysql USE flag:
user $equery hasuse mysql

Show what packages are currently built with the mysql USE flag:
user $eix --installed-with-use mysql

Show what USE flags are available for a specific package:
user $equery uses <package-name>

Quickly add a required USE flag for a package install:
root #echo 'dev-util/cmake -qt4' >> /etc/portage/package.use
Important Portage files[i 1]

/etc/portage/make.conf - Global settings (USE flags, compiler options).
    /etc/portage/package.use - USE flags of individual packages. Can also be a folder containing multiple files.
    /etc/portage/package.accept_keywords - Keyword individual packages; e.g. ~amd64, ~x86, or ∼arm.
    /etc/portage/package.license - Accepted licenses
    /var/lib/portage/world - List of explicitly installed package atoms.
    /var/db/pkg - Contains for every installed package a set of files about the installation.

Log management
genlop

genlop is a Portage log processor, also estimating build times when emerging packages.

Install genlop by issuing:
root #emerge -a app-portage/genlop

You can gather more information on app-portage/genlop by reading its manual page:
root #man genlop

View the last 10 emerges (installs):
root #genlop -l | tail -n 10

View how long emerging LibreOffice took:
root #genlop -t libreoffice

Estimate how long emerge -uND --with-bdeps=y @world will take:
root #emerge -pU @world | genlop --pretend

Watch the latest merging ebuild during system upgrades:
root #watch genlop -unc
Services

Obtain root shell (if the current user is listed in the sudoers list):
user $sudo -s
OpenRC

Start the ssh daemon in the default runlevel at boot:
root #rc-update add sshd default

Start the sshd service now:
root #rc-service sshd start

Check if the sshd service is running:
root #rc-service sshd status
systemd

Start the ssh daemon at boot:
root #systemctl enable sshd

Start the sshd service now:
root #systemctl start sshd

Check if the sshd service is running:
root #systemctl status sshd

http://myridia.com/dev_posts/view/1808

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Gentoo Cheat Sheet 02.09.17

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