[H-GEN] Re: debian [newbie help]

[Martin Pool]

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On 12 Mar 2001, "Andrew T. Scott" <ascott at linuxcare.com> wrote:

> I've been experimenting with debian a bit over the weekend and I'm going
> to have to admit cluelessness.
> 
> Is "xlibs_4.0.2-1.i386.deb" currently broken?

I'm not sure.  "Broken" is not a very useful problem description.
What's actually happening?  Does it not install, or not work, or what?

  $ dpkg --status xlibs

shows my machine running 4.0.2-4, which is presumably current in sid.
Perhaps that one is less broken.  To get there, you can (amongst other
ways) say

  # apt-get update
  # apt-get install --fix-missing
  # apt-get install xlibs

> Is there a way to downgrade to a previous version of things.

In general, no.  However, Debian is trying to let 3.3 and 4.0
co-exist.  If you choose a 3.3 XServer (e.g. xserver-s3) then you can
run that instead, and when you configure it, debconfig will ask you to
choose 3.3 or 4.0 as a default.

> It seems that what is broken, is XFree86-4.0.2, and not 3.3.6.  I'm
> fine with XFree86-3.3.6 but how do I get is back in?  There is a
> huge list of dependencies now from other packages that want >=4.0.1.

Yes, for this reason it's very hard to roll time backwards.  You'd
have to roll back a whole lot of packages, which may themselves have
dependencies, and doing that may reintroduce older fixed bugs.

> Is apt-get *intended* to be used as a tool to do bulk things or as a tool
> to do one or two packages at a time?

Yes, both of those.  At the moment I'm tending to use dselect for bulk
upgrades, but I use apt-get for small tasks.

Before doing any operations, you should download a new index file:

  # apt-get update

Then, if you want a single new package and its dependencies, do this:

  # apt-get install reportbug doxygen hello

If things seem confused, try this:

  # apt-get install -f

If you no longer want it:

  # apt-get remove lilo                  # and stay gone!

If you want all today's new packages:

  # apt-get dist-upgrade

The reason to use dselect rather than dist-upgrade is that you will
also get a chance to see packages recently added to the distribution.

> Upgraded (provided it works) seems to go smoothly in bulk, but
> downgrading???

I think basically Debian says you can't automatically downgrade,
though you can do it by hand by retrieving .debs and installing them
with dpkg.  From their way of thinking: why would you want to?  We
don't want people moving back to random old versions, we want them to
report bugs and install fixes.

> How can I be sure that the debian developers didn't break something (like
> my situation with above package,

Whenever you install software you can't be sure the developers didn't
break anything.  This is the reason why many projects including Debian
have stable and unstable trees, so that risk averse people can let
others find the bugs.  In Debian, as elsewhere, you have a choice
between stability and features.

> (as far as I can tell, there is nothing I can do about it, except
> wait for someone to fix it))?

There's something very useful you can do: file a bug report!  Use the
`reportbug' tool or the bugs.debian.org, which will let you check
whether the bug is already known.  Follow the advice on the website on
including useful information.  Try not to duplicate existing reports,
but rather add any other information you may have.

Basically, if unstable breaks a package, then file a report, hold on
tight for a couple of days, and it will be fixed.  This happens to
particular packages a few times a year on my machine, which I think is
actually pretty good for a development tree.  If the risk of this is
unacceptable, then run stable or testing instead.

If you want to have a very tight grip on your machine's configuration,
then leave apt alone, and download packages by hand and install them
using dpkg, just as for RPM:

  # dpkg --install /tmp/rdiff-213123.12.3_i386.deb

However, if you're going to bother using Debian you might as well use
apt. 

> Is it possible to flip flop between stable and unstable, suplimenting and
> removing packages in each tree on my local system depending upon which one
> I want to run?

It's not impossible, but it's probably counterproductive.  For
example, if one of the new packages introduces an upgrade to an
on-disk data format (e.g the Berkeley DB changes in Perl last year, or
the C++ ABI changes in g++) then you won't be able to smoothly roll
back.

I'd suggest that you create two root partitions, and make a separate
Debian installation into each one, perhaps with shared /etc, /var/ and
/home/.  Then your stable installation genuinely will be stable, and
the unstable one will be exciting, but contained.

-- 
Martin Pool, Human Resource
Linuxcare. Inc.   +61 2 6262 8990
mbp at linuxcare.com.au, http://linuxcare.com.au/
Linuxcare.  Putting Open Source to work.

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