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---
GLEP: 53
Title: Keywording scheme
Author: Fabian Groffen <grobian@gentoo.org>,
        Diego Pettenò <flameeyes@gentoo.org>
Type: Standards Track
Status: Final
Version: 1
Created: 2005-12-11
Last-Modified: 2014-01-23
Post-History: 2007-04-13
Content-Type: text/x-rst
---



Abstract
========

This GLEP is a replacement of the keywording scheme from GLEP 22
[#GLEP22]_.  The current use of keywords is retained in favour of
4-tuple keywords.  This GLEP defines how current keywords are to be
interpreted, and how future keywords should be constructed.


Motivation
==========

Although the state of GLEP 22 [#GLEP22]_ is final, its keywording scheme
was never propagated through the tree.  In fact, 4-tuple keywords are
not used at all.  This GLEP defines a keywording scheme that is
compatible with the scheme that is currently in use.


Rationale
=========

The Gentoo/Alt project deals with different Operating Systems and
architectures.  Recently Gentoo/FreeBSD for Sparc was introduced after
support for x86 platforms.  This yielded in another new keyword.
For these kind of platforms, a single field keyword is not enough to
properly describe the OS and architecture.  While four fields in a
keyword are overkill, two fields in a keyword should be enough for
everyone.


Backwards Compatibility
=======================

The proposed keywording scheme is fully compatible with the current
situation of the portage tree, this in contrast to GLEP 22.  The
variables provided by GLEP 22 can't be extracted from the new keyword,
but since GLEP 22-style keywords aren't in the tree at the moment, that
is not a problem.  The same information can be extracted from the
``CHOST`` variable, if necessary.  No modifications to ebuilds will have
to be made.


Specification
=============

Keywords will consist out of two parts separated by a hyphen (``-``).
The left hand part of the keyword is the architecture, such as `x86`,
`sparc` or `ppc`.  The right hand part indicates the operating system or
distribution, such as `linux`, `macos`, `solaris` or `fbsd`.  If the
right hand part is omitted, it implies the operating system/distribution
type is GNU/Linux.  In such case the hyphen is also omitted.  Examples
of such keywords are ``x86`` and ``sparc-fbsd``.  This is fully
compatible with the current keywords used in the tree.  Examples of
OS/distributions for the right hand side of the keyword are:

::

	(linux)          GNU/Linux (Gentoo biased, but not fixed)
	fbsd             FreeBSD
	macos            Apple Mac OS
	solaris          Sun Solaris

Both architecture as well as OS/distribution are lower-case ASCII
(alpha) numeric character sequences.  A valid keyword matches the
following expression:

	``[a-z0-9]+(-[a-z0-9]+)?``

Note that no limit on the length of both fields in the keyword are
imposed.  However, we cannot overemphasize our preference to keep
keywords small and sensible.

 

.. [#GLEP22] GLEP 22, New "keyword" system to incorporate various
   userlands/kernels/archs, Goodyear,
   (http://glep.gentoo.org/glep-0022.html)


Copyright
=========

This work is licensed under the Creative Commons Attribution-ShareAlike 3.0
Unported License.  To view a copy of this license, visit
http://creativecommons.org/licenses/by-sa/3.0/.