Re: "upgrade" versus "update".
On Fri, 06 Mar 2015 08:53:33 -0800
peter@easthope.ca wrote:
> I get that "dist-upgrade" is the replacement of a distribution
> by the subsequent distribution. Replacement of wheezy by jessie
> for example. What is meant by "upgrade"? In many places it
> appears to be synonymous with update.
>
> For example, googling "site:debian.org update upgrade" yields,
> https://wiki.debian.org/UnattendedUpgrades
> "Running unattended-upgrades:
> Its[sic] purpose is to keep the computer current with the latest
> security (and other) updates automatically."
>
In Debian apt terms, 'update' means to refresh the local list of
current packages, and to notify the user if some installed packages are
no longer the current versions. 'Upgrade' using apt-get is equivalent to
'safe-upgrade' using aptitude, and it means replacing as many packages
as possible with the latest versions without removing packages other
than those actually being replaced. 'Dist-upgrade' with apt-get, or
'full-upgrade' with aptitude does permit removal of packages. They are
not used only to upgrade to another distribution.
Many packages must always be removed in order to move to a 'newer'
distribution (though not necessarily every one), but it is also
sometimes necessary to remove packages in order to upgrade one package,
if for example the functionality of two packages have been merged, or
if a package set is being replaced by a version with a significantly
different architecture, with differently-named component packages. Many
major pieces of software are composed of a number of packages, and
different versions of the software are not always composed of the same
set.
The non-removal types of upgrade will warn if, on completion, they have
not been able upgrade everything, and investigation will usually show
that a removal-type upgrade is necessary to do finish the job. It is
quite rare for stable to need a removal-type upgrade, as its software
is frozen in version terms unless a really serious security problem has
been discovered which cannot be resolved by modifying any current
packages. Using dist-upgrade on stable is pretty much only done to
upgrade to the new stable, but it is used much more often on testing and
unstable, neither of which are ever replaced with newer versions.
--
Joe
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