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Re: Backports installed without prompt if not in base suite: bug or feature ?

Le Mon, Nov 30, 2015 at 09:38:43PM +0900, Charles Plessy a écrit :
> when a package is in the backports suite but not in the base suite, it will
> be installed by "apt install foo" without the need to select the backports
> suite.  For this reason, jessie-backports has not been added to the default
> sources.list in new installations.  (<https://bugs.debian.org/764982>)
> I was wondering if this was an unforseen limitation or a feature ?

Thanks everybody for your answers.

There were long emails which strengthened my understanding of APT, but I hope
that the summary can be concise.

The current behaviour of the backports suite is deeply rooted in how APT works.
Following the "install" command for a package, APT will look at the versions
present in its cache and their priorities ("pin values"), and following the
rules explained the apt_preferences manpage, will either install one of these
versions or do nothing.  In that sense, there is actually no difference between
"installing" a package and "upgrading" a package.  For backport packages
without a counterpart in the base suite, the backports versions are valid
candidtes and will be installed without warning.  This is true as well for
packages in the "experimental" suite.

David wrote that he would like to implement a pattern system inspired from
aptitude, and utilise this to configure and display package listings in a way
that gives a chance to the user to cancel the installation of a backports
package when this installation happens only because there is no version
available in the base suite.

Would such a warning be enough for enabling stable-backports in default
installations ?  Are there front-ends (especially graphical ones) in which it
would be necessary to have a similar warning ?

Have a nice day,

Charles Plessy
Tsurumi, Kanagawa, Japan

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