Re: Apt for RPM question, blocking certain rpms

[Jeff Licquia <jeff@licquia.org>]

On Wed, 2003-10-08 at 14:40, mike808@users.sourceforge.net wrote:
> > For example, Erich could keep his custom RPMs in a local apt repository,
> > and maintain his boxes with a single pin:
> > 
> > Package: *
> > Pin: release o=Museum
> > Pin-Priority: 1001
> 
> I believe you meant "Pin-Priority: 991".
> 990 is the default pin for a package being installed.
> Above 1000 means you allow those packages to be downgraded, I believe.
> So, in your example, I believe that means you _allow_ the Museum packages to
> be downgraded to meet the requirements of a package being installed. And I
> don't think that's what's intended.

No; 1001 means that apt will downgrade if necessary to get the package
from that repository installed.

Maybe an example will help.

Package: foo
Pin: release o=Bar
Pin-Priority: 991

Package foo 1.0 is in Bar, and package foo 1.1 is in Baz, another
repository.  1.1 is also installed.  "apt-get dist-upgrade" will do
nothing with this, since 1.1 is already installed on the system.

Now up the Pin-Priority to 1001.  Now, "apt-get dist-upgrade" will
install foo 1.0 from Bar, downgrading from 1.1.  And later, when foo 1.2
appears in Baz, apt will ignore it.

It's a little confusing, but the rule of thumb is: higher pin priorities
are always stronger.  If you think of currently installed packages as
having a pin priority of 1000, it makes sense.  (That's kind of how it's
implemented, as a matter of fact; currently installed packages have a
pin priority of 1000 as regards older package versions, but 100 as
regards newer ones.)

I interpreted Erich's request to force certain packages on his system,
no matter the version numbers.  That's what pin priorities over 1000 do.

> BTW, my exposure to preferences has been with Xandros, and it is to do
> exactly that - prevent Xandros-specific packages from being upgraded to that
> package from Debian.
> 
> > On Debian, dpkg holds are nice and quick compared to setting up pins,
> > but if a good UI were ever written for pinning, that would probably be
> > the best place to set these things.
> 
> Are there any decent starts at it yet? Name names. I wouldn't mind taking a 
> look at 'em.

None that I know of.  I have a few vague ideas, but nothing implemented.

Since you have experience, how do you think you'd want to see the UI?
-- 
Jeff Licquia <jeff@licquia.org>

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