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Gentoo cheatsheet

Written by Solène, on 05 July 2021.
Tags: #linux #gentoo #cheatsheet

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Introduction §

This is a simple cheatsheet to manage my Gentoo systems, a linux distribution source based, meaning everything installed on the computer must be compiled locally.

Gentoo project website

Upgrade system §

I use the following command to update my system, it will downloaded latest portage version and then rebuild @world (the whole set of packages manually installed).

emerge-webrsync 2>&1 | grep "The current local"
if [ $? -eq 0 ]

emerge -auDv --with-bdeps=y --changed-use --newuse @world

Use ccache §

As you may rebuild the same program many times (especially on a new install), I highly recommend using ccache to reuse previous builded objects and will reduce build duration by 80% when you change an USE.

It's quite easy, install ccache package, add 'FEATURES="ccache"' in your make.conf and do "install -d -o root -g portage -p 775" /var/cache/ccache and it should be working (you should see files in the ccache directory).

Gentoo wiki about ccache

Use genlop to view / calculate build time from past builds §

Genlop can tell you how much time will be needed or remains on a build based on previous builds information. I find it quite fun to see how long an upgrade will take.

Gentoo wiki about Genlop

View compilation time §

From the package genlop

# genlop -c

 Currently merging 1 out of 1

 * app-editors/vim-8.2.0814-r100 

       current merge time: 4 seconds.
       ETA: 1 minute and 5 seconds.

Simulate compilation §

Add -p to emerge command for "pretend" and pipe it to genlop -p like this

# emerge -av -p kakoune | genlop -p
These are the pretended packages: (this may take a while; wait...)

[ebuild   R   ~] app-editors/kakoune-2020.01.16_p20200601::gentoo  0 KiB

Estimated update time: 1 minute.

Using gentoolkit §

The gentoolkit package provides a few commands to find informations about packages.

Gentoo wiki page about Gentoolkit

Find a package §

You can use "equery" from the package gentoolkit like this "equery l -p '*package name*" globbing with * is mandatory if you are not looking for a perfect match.

Example of usage:

# equery l -p '*firefox*'
 * Searching for *firefox* ...
[-P-] [  ] www-client/firefox-78.11.0:0/esr78
[-P-] [ ~] www-client/firefox-89.0:0/89
[-P-] [ ~] www-client/firefox-89.0.1:0/89
[-P-] [ ~] www-client/firefox-89.0.2:0/89
[-P-] [  ] www-client/firefox-bin-78.11.0:0/esr78
[-P-] [  ] www-client/firefox-bin-89.0:0/89
[-P-] [  ] www-client/firefox-bin-89.0.1:0/89
[IP-] [  ] www-client/firefox-bin-89.0.2:0/89

Get the package name providing a file §

Use "equery b /path/to/file" like this

# equery b /usr/bin/2to3
 * Searching for /usr/bin/2to3 ... 
dev-lang/python-exec-2.4.6-r4 (/usr/lib/python-exec/python-exec2)
dev-lang/python-exec-2.4.6-r4 (/usr/bin/2to3 -> ../lib/python-exec/python-exec2)