GLEP 54: scm package version suffix

Author Piotr Jaroszyński <>
Type Standards Track
Status Deferred
Version 1
Created 2007-12-09
Last modified 2014-01-23
Posting history 2007-12-09
GLEP source glep-0054.rst


Marked as deferred by GLEP editor creffett due to inactivity


This GLEP proposes addition of a new special package version suffix - scm - for ebuilds checking out source directly from a source code management system.


Currently there is no standard way of identifying SCM ebuilds. Using 9999 as the version is pretty common, but it is handled like any other ebuild and hence portage cannot provide any additional features for packages with such a version. Another way is adding a separate package with a -cvs suffix in its name, but that forces the author to use || ( cat/pkg cat/pkg-cvs ) dependencies. The closest to what is proposed in this GLEP is the cvs version part, but its implementation is of very limited use. It has strange comparison rules, no documentation, has been used sparingly (if ever) and has a misleading name.

The possibility for package managers to recognise SCM ebuilds would allow them to add features dedicated specially to said ebuilds. One such feature could be automatic re-installation of SCM packages once a day or week. Any specifications for such features are beyond the scope of this GLEP.


scm is a special suffix. It can be used on its own, but also in any other valid version spec, just before the place where revision would go. And just like revision it can be used only once in a version spec, e.g.:

  • cat/pkg-1.0_alpha0-scm
  • cat/pkg-1.0_alpha-scm
  • cat/pkg-1.0-scm-r3
  • cat/pkg-1-scm
  • cat/pkg-1-scm-r2
  • cat/pkg-scm

These package atoms are sorted in ascending order (see Version Comparison).

Version Comparison

The addition of the scm suffix yields changes in version comparison:

  • When comparing version components from left to right the scm component has the highest priority over other version components. Hence pkg-1_alpha-r3 < pkg-1-scm, 'scm' is greater than 'alpha-r3'.
  • Current suffixes with no number part no longer default to zero if they are followed by an scm suffix. If that's the case the number part is considered to be of a maximum value. Hence 1_alpha2-scm < 1_alpha-scm, but still 1_alpha == 1_alpha0. The rationale behind this choice is to allow multiple branches. For instance imagine a package with an alpha branch and multiple scm releases, as the following: alpha-scm, alpha2-scm, alpha3-scm and so forth. The desired outcome is for alpha-scm to be greater than all other branches of the same tree.

Example parsing:

  • cat/pkg-scm > cat/pkg-1
    When parsing from left to right the first difference is scm and 1. cat/pkg-scm wins.
  • cat/pkg-1-scm > cat/pkg-1.0-scm
    When parsing from left to right the first difference is scm and 0. cat/pkg-1-scm wins.
  • cat/pkg-1_alpha-scm > cat/pkg-1_alpha1-scm
    In the first package version alpha doesn't have a number part and is followed by an scm suffix, hence it is considered to have a maximum value as the number part. When parsing from left to right the first difference is the number part of the alpha suffix. Maximum value yielded by the following scm suffix wins with 1.

List of version specs in ascending order:

  • 1
  • 1.1-scm
  • 1.2_alpha-scm
  • 1.2_beta_p
  • 1.2_beta_p0-scm
  • 1.2_beta_p1-scm
  • 1.2_beta_p-scm
  • 1.2_beta1_p-scm
  • 1.2_beta10
  • 1.2_beta10_p1-scm
  • 1.2_beta10-scm
  • 1.2_beta-scm
  • 1.2
  • 1.2-scm
  • 1.2-scm-r1
  • 1-scm
  • 10
  • scm
  • scm-r3

Backwards Compatibility

Portage versions prior to (included in 2007.0) don't handle arbitrary version suffixes and die during various tasks making portage hard or impossible to use. Later versions just ignore them displaying warnings. Hence use of scm suffixes in gentoo-x86 tree will probably have to wait till 2008.0 release or later.