Backporting and package versions on Ubuntu

Like all enterprise Linux distributions, Ubuntu backports patches so updates do not break applications due to version incompatibilities. Backporting means software is patched to fix bugs and security issues but software version numbers are not changed.

Ubuntu only packages the latest versions of software when there is a new Ubuntu release. For the life of each Ubuntu release, Ubuntu keeps software patched without changing software version numbers. By not constantly upgrading versions of all libraries and packages, Ubuntu ensures long-term security without introducing breaking changes.

Package versioning with patches

A package’s version number contains two parts:

1. The version of the software provided by the package.
2. A release identifier that indicates the patches applied to the software in the package.

For example, in the following package version number:

3.0.13-0ubuntu3.7

The software version is 3.0.13 and the release identifier is 0ubuntu3.7.

When Ubuntu builds an updated package that includes a new patch, only the release identifier is changed. If the release identifier for the updated package is 0ubuntu3.8, then the full version number of the new package is:

3.0.13-0ubuntu3.8

For an available package to be considered a newer version of an installed package, only the release identifier needs to be higher. The version of the packaged software does not need to change.