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Gentoo Overlays: Users' Guide

Content:

1.  Introduction

Audience

This document has been written for all users of Gentoo. If you are a Gentoo developer or Gentoo staff member, and you want to be able to manage your own overlay, please see the Developers' Guide.

What Are Overlays?

"Overlays" are package trees for Portage. They contain additional ebuilds for Gentoo. They are maintained by Gentoo developers and projects but distributed separately from the main Portage tree.

Why Use Overlays?

People create overlays for all sorts of reasons. Here are a few of the main ones:

  • If you modify an ebuild in /usr/portage, your change will be lost the next time you emerge --sync. But, if you put your modified ebuild into an overlay, your change is safe from emerge --sync.
  • Because overlays are not the main Gentoo Portage package tree, they're a great place to develop and test an ebuild without fear of breaking the main Gentoo Portage package tree.
  • Not every ebuild belongs in the Gentoo Portage package tree. An overlay is a great place to store an ebuild until it is ready to go into the Gentoo Portage package tree.

What is the Gentoo Overlays Project?

Gentoo Overlays provide social workspaces to allow Gentoo projects, developers and users to collaborate together on tomorrow's Gentoo packages. We do this by hosting overlays for Gentoo projects, developers, and users.

Are All Official Overlays Hosted On overlays.gentoo.org?

No. Gentoo developers are free to put their overlay wherever suits them best; they don't have to use overlays.gentoo.org if they don't want to.

2.  Getting Started With Overlays

Use layman to easily install and update overlays over time.

Installing Layman

Before you install layman it is worth mentioning that you probably want USE="git subversion" for it. After adjusting use flags, to install layman you run:

Code Listing 2.1: Installing layman

# emerge layman

Code Listing 2.2: Telling Portage about layman-fetched repositories

(for layman 1.1)
# echo "source /usr/portage/local/layman/make.conf" >> /etc/portage/make.conf

(for layman 1.2)
# echo "source /usr/local/portage/layman/make.conf" >> /etc/portage/make.conf

(for layman 1.3 and later)
# echo "source /var/lib/layman/make.conf" >> /etc/portage/make.conf

Note: Layman will create /var/lib/layman/make.conf once you add your first overlay. But if you do not plan to install an overlay immediately you should ensure that this file actually exists and contains the empty variable PORTDIR_OVERLAY. Otherwise Portage will complain. You can run echo PORTDIR_OVERLAY=\"\" > /var/lib/layman/make.conf in order to have the file created correctly.

Listing The Available Overlays

To see the list of overlays available, run:

Code Listing 2.3: Listing the available overlays

# layman -L

Installing An Overlay

To install an overlay on your computer, run:

Code Listing 2.4: Adding an overlay

# layman -a <overlay-name>

For example, to install the PHP overlay, run:

Code Listing 2.5: Adding the PHP overlay

# layman -a php

Installing Packages From An Overlay

After installing an overlay, you can install packages from it by running:

Code Listing 2.6: Installing a package from an overlay

# emerge -av <category>/<package>

Portage automatically searches your Gentoo main tree (in /usr/portage) and all of the overlays that you've installed, and picks the latest version of the package that it can find.

If Portage isn't picking up the package from the overlay, that's normally because the package is marked ~arch, where "arch" is the architecture of your computer. You'll need to keyword the package as explained in the Gentoo Handbook.

Updating An Overlay

To keep your installed overlays up to date, run:

Code Listing 2.7: Updating all installed overlays

# layman -S

Important: Please don't run this more than once a day, or you'll put too much strain on Gentoo's infrastructure.

3.  How To Get More Involved

Introduction

All Gentoo developers were users of Gentoo before they became developers and still are users. Our users aren't just the reason Gentoo exists today; they're our future volunteers too.

If you start contributing to a project, we'll give you write access to the project's overlay, and we'll provide mentors to help you contribute. Eventually, if we like what you do and the way you do it, we'll invite you to go the whole hog and become a full Gentoo developer.

How To Get Started

If you want to contribute to an overlay, the best approach is to build a good working relationship with the Gentoo developers who are responsible for the overlay. You can find out who is responsible for each overlay by going to overlays.gentoo.org's homepage, and clicking on the link for the overlay in question.

Different developers prefer to be contacted in different ways. Some hang out on IRC, and may have their own channels for their projects. Examples of these include the PHP project (#gentoo-php), and the Webapps project (#gentoo-web). Others prefer to be contacted by email only. The only way you'll find out is to try and make contact, and take it from there. Commonly people in #gentoo-bugs on freenode IRC know where to find the people in question.

Working With Subversion

Subversion is one version control software we use to manage the contents of our overlays. If you have never used Subversion before, the Subversion book is an excellent way to learn Subversion. You can buy it in dead-tree format if you prefer or read it online for free.

Working With Git

Git is another version control software we use to manage the contents of our overlays. To get in touch with it, see the tutorial provided on the homepage.

Further Information

The Gentoo project (or developer) you're working with should be able to provide you with any further help and assistance that you need.

4.  Frequently Asked Questions

Q: Do you host overlays for users?

A: Yes, we do. Please see this post for instructions on how to host your overlay on Gentoo infrastructure.



Print

Page updated April 6, 2013

Summary: This guide helps users understand how to use the Gentoo Overlays service.

Stuart Herbert
Author

Markus Ullmann
Author

Joshua Saddler
Editor

Pavlos Ratis
Editor

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