Ubuntu – How to know default software version for all Ubuntu software for a specific Ubuntu version

Yes, just as upgrades from LTS to LTS are supported, upgrades from an intermediate release to the next LTS are supported.

Historically this is only supported by manually changing your apt sources, since update-manager / do-release-upgrade require you to go step by step.

But since 13.04 will go end of life before 12.10, we will need to skip over 13.04 in the upgrade path. This will be implemented on the server (and with an SRU of the update-manager package to 12.10) to show the direct upgrade as an available option.

First off, an important clarification:

The terms "Stable Release Updates" and "Security Updates" (don't forget them!) apply to packages in main, universe, restricted and multiverse. PPAs or other third-party repositories may have their own release schedules and policies. In your screenshot I see "google-chrome-stable" -- this is not a Ubuntu package and it does not follow the Ubuntu release schedule.

Having said that, here's what you asked for:

• For every Ubuntu update, the point of reference is the Launchpad bug. This is where you can find most of the information related to the problem(s) and solution(s).

  You can get the bug numbers by checking the changelog of each package. For example, as of writing, this is the last entry from apt-get changelog nautilus:

  nautilus (1:3.14.2-0ubuntu9.1) vivid; urgency=low
  
    * debian/patches/ignore-no-desktop-if-not-first-launch.patch:
      - Don't shut off the desktop when external application calls nautilus
        --no-desktop on a running GNOME desktop. (LP: #1453655)
  
   -- Chow Loong Jin <hyperair@debian.org>  Wed, 24 Jun 2015 11:50:03 +0800
  

  As you can see, the log entry refers to bug #1453655.

  For security bugs, generally the bug report is private (to prevent malicious people from accessing critical information) and, generally, instead of the Launchpad bug number you'll find the CVE number.

• Patches applied by Ubuntu (or by Debian) are in the source package, in the debian/patches directory. If you want to download the source packages for Nautilus, use apt-get source nautilus.

  If a Stable Release Update or a Security Update introduces a new version of the software (e.g. a new version of Firefox), you'll have to look upstream for the full delta.

  Not all package sources are available under version control (git, hg, bzr, ...).

• Discussion generally happen on Launchpad. If necessary, the ubuntu-devel mailing list may be used too.

• People responsible for updates are the people who provide the updates (package maintainers or contributors), the Ubuntu SRU Team and the Ubuntu Security Team.

  Note that not all of these people are Canonical employees. Be kind and don't forget those contributors who use their spare time to maintain stability and security in Ubuntu :-)

• The process for Stable Release Updates and Security Updates is documented on the Ubuntu Wiki: https://wiki.ubuntu.com/StableReleaseUpdates and https://wiki.ubuntu.com/SecurityTeam/UpdateProcedures