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Re: More info - was [Re: Synaptic fails to fix broken packages]


On Fri, Oct 05, 2018 at 07:03:13AM -0400, rhkramer@gmail.com wrote:
> On Friday, October 05, 2018 06:06:25 AM Reco wrote:
> > On Fri, Oct 05, 2018 at 04:57:36AM -0500, Richard Owlett wrote:
> > > Can someone point me to a discussion of why one would chose a particular
> > > option?
> > 
> > Why do you need a discussion of that if you have apt-get(8)?
> > 
> > upgrade is used to install the newest versions of all packages currently
> > installed on the system from the sources enumerated in
> > /etc/apt/sources.list. Packages currently installed with new versions
> > available are retrieved and upgraded; under no circumstances are
> > currently installed packages removed, or packages not already installed
> > retrieved and installed. New versions of currently installed packages
> > that cannot be upgraded without changing the install status of another
> > package will be left at their current version.
> > 
> > dist-upgrade in addition to performing the function of upgrade, also
> > intelligently handles changing dependencies with new versions of
> > packages.
> I'm not the op, but I didn't quite get that (so I did try to read the relevant 
> portions of apt-get (8), and here is my understanding.
> As stated clearly, upgrade will not necessarily upgrade everything that could 
> be upgraded, specifically if installing new dependencies would disable some 
> other package.

It's the 'installed packages removed' part that people are usually are
worrying about ☺
'Installing by dependency' is something that only worries purists like
me ☺.

> dist-upgrade will attempt to handle those situations, but may end up disabling 
> some packages.

Not 'disabling'. 'Removing' aka 'it's not here anymore and you cannot
install it back'.

> dist-upgrade apparently has some mechanism to decide which 
> packages are more important, and upgrade those while (possibly) disabling some 
> packages that it deems less important.

And the mechanism is called 'dependency conflict resolution'.

> (Maybe that mechanism is described elsewhere in apt-get (8).)

They call it, to quote '"smart" conflict resolution system', but that's

> Is my understanding correct?

Close enough.

> Can someone describe (or point to) a description of how dist-upgrade 
> determines the more important app?  (Oh, I'm guessing it has to do with the 
> whatever it is called label on each package, something like required, 
> recommended, ... (I may be using the wrong words).  Supposed dist-upgrade has 
> to choose between two packages that have the same label?

I'm afraid I lost you here.
Is 'more important' refers to dependency alternatives? Package
priorities? Something else?
By 'label' did you mean 'Tag' field or something else?

Let's try to do it this way.
Execute 'apt show bash', observe there result.
Ask your question once more, but this time use 'apt show bash' as a


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