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What does a notation such as "works-with::image:raster" mean?
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It means that the facet (the point of view from which we look at the packages)
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is "works-with", and that the tag (what kind of data this package can handle)
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ignored by package managers, using debtags instead.
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How come there are different sets of tags in the Packages file and in ``/var/lib/debtags``?
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-------------------------------------------------------------------------------------------
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There are a few reasons:
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* Debtags supports merging different tag sources: for example, iterating.org
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provides a tag source with package rankings and debtags is able to download
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it and merge it to the other tags. Tag sources are listed in
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``/etc/debtags/sources.list``. This also allows some of us to use the
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unreviewed tags on Alioth instead of the ones in the Package database.
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* For many applications the tags are easier to access when aggregated on a
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small file rather than by parsing the very large package database
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* Finally, the debtags database in ``/var/lib/debtags`` is also indexed for
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Have the Packages file as the primary tag storage has never been the main idea,
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although it's turned out to be useful to allow tags to be useable in
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software such as apt-cache, aptitude and grep-dctrl without them having to be
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modified to access an extra database.
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The Packages file has tags like ``network::{client,server,service}`` and this breaks ``grep-dctrl``
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---------------------------------------------------------------------------------------------------
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Those compressed tags are there because APT does not like long lines.
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You can use ``debtags dumpavail`` to feed data to grep-dctrl without the
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``debtags dumpavail`` also supports tag expressions, so you can even run
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debtags dumpavail 'role::program && game::*' | grep-dctrl <options>
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How can I experiment writing applications using debtags?
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--------------------------------------------------------
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You can have a look at `libapt-front-dev`_, which allows access to both debtags
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and apt package data and is a really good C++ library. Thanks to the work of
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Torsten Marek, it may soon have Python bindings.
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For C++, have a look at `libept-dev`_, which allows access to both
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debtags and apt package data.
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For Python, the `python-debian`_ package has a good ``debtags`` module and
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various interesting code examples.
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, which also has python__ and perl__
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.. _libapt-front: http://libapt-front.alioth.debian.org/
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.. _libdebtags1-dev: http://packages.debian.org/libdebtags1-dev
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.. _libapt-front-dev: http://packages.debian.org/libapt-front-dev
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.. _libept-dev: http://packages.debian.org/libept-dev
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.. _packagebrowser: http://debian.vitavonni.de/packagebrowser/
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.. _packagesearch: http://packagesearch.sourceforge.net/
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.. _theorical foundation: http://debtags.alioth.debian.org/faceted.html
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.. _Alioth project: http://debtags.alioth.debian.org/
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.. _python-debian: http://packages.debian.org/python-debian
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doc/faq.rst
