[kwlug-disc] why would you do "apt-get dist-upgrade" regularly?

[Chris Frey]

On Sat, Aug 15, 2009 at 09:18:50AM -0400, Robert P. J. Day wrote:
>   now let's say i do a "full-upgrade".  what happens?  as i understand
> it, even though my /etc/apt/sources.list explicitly refers to "lenny,"
> will that take me to "squeeze?"  and if it does, will that upgrade
> process update my /etc/apt/sources.list to reflect that new release?

As Lori mentioned, there's two ways to refer to a release.  Consider these
/etc/apt/sources.lists lines:

   deb http://ftp.us.debian.org/debian/ lenny main contrib non-free

and

   deb http://ftp.us.debian.org/debian/ stable main contrib non-free

Currently these point to the same repositories.  But once Squeeze
becomes the next stable, the second line will point to squeeze automatically,
since the "stable" symlinks will have been updated on the servers.

The first line will stay with what you have, until *you're* ready to
upgrade.

The different between upgrade and dist-upgrade is that dist-upgrade
will take more liberties in the upgrade.  It will be more flexible in
the packages it chooses.  Normally, this flexibility is not required,
since doing a security update means going from foo-1.2.3 to foo-1.2.3-1lenny1
and nothing fancy is required.

But jumping major versions may require changing whole packages.  Perhaps
iceweasel is now called superfrozenrat or something.  Such an upgrade
is not a simple direct line, but both are web browsers, and both
will provide that meta functionality.  The package maintainers will
keep the package meta data such that a dist-upgrade will likely find
the right path for you to take.

So, in the above example, apt-get upgrade might fail, saying that
iceweasel is not available to upgrade, and another package depends on
web browser.  apt-get dist-upgrade will take a higher view and actually
remove iceweasel and install superfrozenrat instead, automatically.

So goes my understanding, anyway.  Dist-upgrade will not jump major
versions against your will, it just changes the logic of what is
acceptable to upgrade.

- Chris