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Re: How do you "move to testing/etch"?

Joseph Haig wrote:
> --- marc <gmane@auxbuss.com> wrote:
> > Hi,
> >
> > I've scoured the archives and docs, and googled the globe, but I
> > cannot
> > find an explanation for safely moving - as safe as it can be - from
> > stable/sarge to testing/etch.


> > My best guess is to edit /etc/apt/sources.list, and apt-get update,
> > apt-get dist-upgrade, but can anyone point to a good description of the
> > process, please.

> I am by no means an expert, but I believe that your 'best guess' is all
> that is needed - it works for me, at least.  So in summary, edit
> /etc/apt/sources.list, replacing sarge or stable in each line with etch
> or testing and then execute the following:
> $ apt-get update
> $ apt-get dist-upgrade


Here a "man apt_preferences" would help a lot. I was also confused by
the way in which packages are chosen from the repositories one has in
/etc/apt/sources.list, until I began editing /etc/apt/preferences (for
which I took a look at the man page of "apt_preferences").

I can't say my grasp of the matter is perfect, but this is what I
understand: aptitude (or apt-get), when called with the "update"
argument, connects to all of the repositories you specify, and builds,
not only a list of available packages, but also different versions (if
it finds more than one), the release to which each one belongs, and the
preference order of the versions, according to some settings, which
give each package version an "score". Then aptitude upgrade will
install not the newest versions of each package, but the one with
highest score.

That part about the score is the one you tune with
/etc/apt/preferences. In the absence of this file, how does apt know
what to install? More or less it installs the newest version it finds
in the repositories. If you set your /etc/apt/preferences to giving the
Etch packages say 500 points by default, and you have Sid and Etch
repositories, and package "whatever" is 1.1 in Etch, and 1.3 in Sid,
then an aptitude update will give the Sid version say 200 points
because it is the newest it finds, but then the 500 points the 1.1 Etch
starts with win, and you get the Etch package.

However, if you had the 1.2 version installed, and aptitude gave the
1.1 Etch version a penalty of -400 points because it is older than the
one already installed, then the 1.3 Sid would win 200 vs. 100 (The
figures are completely made up by me).



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