General
-------

The dist-upgrader is designed to make upgrades for ubuntu (or similar
distributions) easy and painless. It supports both network mode and
cdrom upgrades. The cdromupgrade will ask if it should use the network
or not. There is a wrapper script "cdromupgrade" (that assumes the
file of the upgrade life in
CDROM_ROOT/dists/stable/dist-upgrader/binary-all/) that can be put
onto the CD and it will support upgrades directly from the CD.


Environment
-----------
The following environment variable will be *honored*:

RELEASE_UPGRADE_NO_FORCE_OVERWRITE:
- if that is set, no --force-overwrite is used

RELEASE_UPRADER_NO_APPORT:
- if that is set, apport is not run in case of package install falures

RELEASE_UPRADER_ALLOW_THIRD_PARTY:
- if that is set, third party repositories will not be commented out
  but instead tried to be upgraded



The following environment variable will be *set* by the upgrader:
RELEASE_UPGRADE_IN_PROGRESS:
- set to "1" if a release-upgrade is running (and not a normal
  package/security upgrade)
RELEASE_UPGRADE_MODE:
- either "desktop" or "server" 


Configuration
-------------

The DistUpgrade.cfg format is based on the python ConfigParser.

It supports the following sections:

[View] - controls the output 
Depends:
  Packages that must be installed to the version specified (just like
  a regular depends line in a pkg).
[$view-used]
Depends: just like the global "view" depend but only evaluated when the
         specific view is in use

[Distro] - global distribution specfic options
BaseMetaPkgs: 
  the basic meta-pkgs that must be installed (ubuntu-base usually)
MetaPkgs: 
  packages that define a "desktop" (e.g. ubuntu-desktop)
PostUpgrade{Install,Remove,Purge}: 
  action right after the upgrade was calculated in the cache (marking 
  happens *before* the cache.commit())
ForcedObsoletes: 
  Obsolete packages that the user is asked about after the upgrade (marking 
  happens *after* the cache.commit())
RemoveEssentialOk:
  Those packages are ok to remove even though they are essential
KeepInstalledPkgs:
  If the package was installed before, it should still be installed
  after the upgrade
KeepInstalledSection:
  Packages from this section that were installed should always be
  installed afterwards as well (useful for eg translations)

[$meta-pkg]
KeyDependencies:
  Dependencies that are considered "key" dependencies of the meta-pkg to
  detect if it was installed but later removed by the user
PostUpgrade{Install,Remove,Purge}: 
  s.above
ForcedObsoletes: 
  s.above

[Files] - file specific stuff

[Sources] - how to rewrite the sources.list

[Network] - network specific options

[PreRequists] - use specific packages for dist-upgrade 
Packages= List of what packages to look for
SourcesList=a sources.list fragment that will be placed into 
            /etc/apt/sources.list.d and that contains the backported pkgs