dpkg question: preinst run before Depends:?

[Ian Jackson <ian@chiark.greenend.org.uk>]

Christian Schwarz <schwarz@monet.m.isar.de>:
> Is a preinst script run before any depending packages are unpacked?

No.  Programmer v2.1.1.0 s8.2:
  All but Pre-Depends (discussed below) take effect only when a package
  is to be configured. They do not prevent a package being on the system
  in an unconfigured state while its dependencies are unsatisfied, and
  it is possible to replace a package whose dependencies are satisfied
  and which is properly installed with a different version whose
  dependencies are not and cannot be satisfied; when this is done the
  depending package will be left unconfigured (since attempts to
  configure it will give errors) and will not function properly.

> We are currently converting tetex's preinst script in a Perl script
> that depends on dpkg-perl, so the question is wheter tetex-* has to
> "Depend" on dpkg-perl or "Pre-Depend" on it.

Policy s3.1.4:
  Do not use Pre-Depends or Essential: yes unless your package is
  absolutely vital to the functioning of the system and the installation
  of other packages. Do not do either of these things without
  consultation with the distribution maintainers or on debian-devel.

So you should not make tetex's preinst depend on dpkg-perl.  Only
Essential packages are guaranteed to be available in preinst scripts.

Ian.


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