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Re: Versioned dependencies and maintainer scripts

On Mon, Jun 25, 2018 at 11:10:51AM -0600, Daniele Nicolodi wrote:
> On 6/25/18 1:04 AM, Simon McVittie wrote:
> > For the postinst, you can rely on the updated init-system-helpers being
> > at least unpacked (which should be enough, because i-s-h is Essential,
> > so it's required to provide its core functionality while merely unpacked
> > and not yet configured).
> > 
> > The difference for Pre-Depends is that it would give you the ability to
> > assume that i-s-h has been configured (fully installed) before your
> > postinst runs. I don't think you need that here.
> > 
> > In the postrm, you can't normally rely on having your package's
> > dependencies still installed, but init-system-helpers is Essential so
> > it should still be there, and we don't officially support downgrades so
> > i-s-h should still be at least the required version.
> Only tangentially related: does that mean that we can drop the checks
> for the presence of deb-systemd-helper in the postrm maintainer scripts
> injected by dh_installsystemd (for example [1]) and simplify them a bit?

"purge" might happen decades (sic) after "remove" with no dependencies 
installed and packages that are essential today no longer being essential.

> Cheers,
> Dan



       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed