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Re: Delayed ldconfig execution in postinst step



Eduard Bloch <edi@gmx.de> wrote:

>> dpkg-hook /usr/lib/man/update-manpages  - run only once in total
>> dpkg-hook --on-depends foobar ldconfig  - run once before depends of foobar
>
> What is a depends? Do you mean dependency or dependents?

I think he means dependents:  If package foo depends on library foobar,
dpkg/apt can unpack and configure-without-ldconfig all packages that
don't depend on foobar, but it must run ldconfig before any package that
declares: "Depends: foobar" is configured.

> Further, I would not depend on package installation operations but
> instead invent something like "dpkg-hook --execute ldconfig" to run
> outstanding tasks noted under the name "ldconfig".

This I don't understand...

> That's all. IMO a matter of few hours to implement and test (in Perl).

*And* it's a matter of setting up a good policy which hooks will be
implemented/allowed.  The problem is that if anything goes wrong when
executing a postponed command, dpkg has no way to tell which package
caused the failure, and all packages involved will be marked as
configured fine, while in fact they may be non-functional.

Therefore it is crucial that only commands 

- that cannot sensibly be assumed to fail, und any circumstances
  including f'cked up filesystems,

- or that can safely be assumed to exit with a clear,
  user-understandable error message

can be allowed.  Remember, the *user* has to decide what to do, and
against which package a bug should be filed.

Regards, Frank
-- 
Frank Küster
Single Molecule Spectroscopy, Protein Folding @ Inst. f. Biochemie, Univ. Zürich
Debian Developer (teTeX)



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