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apt-get and aptitide were two missing competitors of the misc competition. However it is important and interesting how these two tools compete against other solvers submitted to MISC. In this post I want to present two simple tools to convert cudf documents to something that apt-get based tools can handle. Cudf and debian share many characteristics but also have important semantic differences. One important difference is about installing multiple versions of the same package. Since this is allowed in cudf, but not in debian, we can use apt-get and aptitude only to solver cudf problems that respect this constraint, ruling out, for example, all cudfs from the rpm world. Another difference to take care is about the request semantic. In cudf, request can contain version constraints. For example, one can ask to upgrade the package wheel to a version greater then 2. Since it is not possible to translate directly this request in cudf we are forced to add a dummy package encoding the disjunction of all packages that respect this constraint. This problem does not arise with remove request as the refer always to the currently installed package.

Apt-get needs two files : The Packages file that contains the list of all packages known to the meta-installer and the status file that contains the list of packages that must result currently installed. To generate these files I wrote a small utility using the dose3 framework imaginatively called cudftodeb . This tool gets a cudf and produces three files : Packages, status and Request with the Request file containing the list of files to install or remove in a syntax compatible with apt-get .

In other to run apt-get/aptitude with these files, you would need a simple bash script. You can find details here for apt-get and here for aptitude. Most important option is the -s used to simulate an installation.

With the -v option of apt-get we can generate a parsable solution. This output is the piped through an other tool called aptgetsolutions in order to produce a cudf solution closing the circle.

For example, this is the trace produced by aptitude when trying to solve the legacy.cudf problem :

Not the package dummy_wheel used to encode the upgrade request of wheel>>2. This dummy package encodes the request as a dependency :

One last remark about apt-get. I just run on this bug today using an old version of apt-get that is shipped with lenny. For our experiments we are using only the latest version of apt-get in debian testing.