The context

I wanted to audit my installed packages. I created a Python helper invoking dpkg-query, to create a packages database using Python dictionary and lists. The helper is smart enough to check dependencies are indeed present in the dictionary cloning the installed packages database. I get an error with the wings3d package: the helper notified me a package named erlang-abi-13.a is missing. Synaptic tells me this package is not installed. It still list this package as a wings3d dependency, but displays it in dependency, using italic instead of regular font.

The question(s)

What does it mean when Synaptic displays a dependency using italic? How a dependency may be missing while the package seems not to be broken?


All packages starting with erlang-abi, are virtual packages. This will be apparent from the apt-cache output:

apt-cache show erlang-abi-15.b
N: Can't select versions from package 'erlang-abi-15.b' as it is purely virtual
N: No packages found

Your helper is not accounting for virtual packages so it fails. This is also why Synaptic shows the packages with italics.

  • I accepted your answer, although it did not directly answered the initial question. Starting from the useful track you provided, I figured it all, and updated the initial post to add the effective answer. Feel free to review it if you wish. – Hibou57 Jan 24 '14 at 5:12
  • @Hibou57 reading your question section, you ask "Why the italics" and "Why it shows broken while it isn't". If you are going to answer your (other) question, please write a new question since it doesn't fit the Q&A. – Braiam Jan 24 '14 at 5:23
  • OK, I've made another edit. Hope this one better preserve the Q&A style. – Hibou57 Jan 24 '14 at 6:25


apt-cache depends erlang-abi-13.a # see what depends upon it


apt-cache rdepends erlang-abi-13.a # see what it depends upon

Then do the same of wings3d. to see if erlang-abi-13.a is listed.

Packages and requirements can get a bit mixed up when you do a Distribution updates. That might be the cause of this.

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