Sometimes, it is necessary for a package to get a new name. Although this should rather seldom be the case, there are some situations when it makes sense, for example when the name of the upstream application changes. Of course an apt-get dist-upgrade should still seamlessly upgrade the package, best by completely removing the old package and installing the new one as a replacement.

Transition package method

Basically, the solution is to define a binary dummy package with the same name as the old package in the control file of the new package. The new source package takes over the binary dummy package, and the old source package, which is then binaryless, will be cleaned up by rene, an archive cleanup tool.

Assume that the last upstream version of the old package "oldname" was 1.5 and the package was renamed to "newname" for version 2.0.

Then, the dummy package is defined like this in debian/control:

 Package: oldname
 Depends: newname, ${misc:Depends}
 Architecture: all
 Priority: optional
 Section: oldlibs
 Description: transitional package
  This is a transitional package. It can safely be removed.

This entry defines the binary dummy package. It will get version 2.0-1 and automatically be pulled in by an apt-get dist-upgrade if an earlier version of oldname was already installed. Be sure to use the term "transitional package" in the long description as various tools (lintian, deborphan, debfoster, etc.) look for exactly those two words.

The package only installs the mandatory files in /usr/share/doc/oldname and possibly some compatibility symlinks, see below.

Since it depends on newname, it also installs the new package.

Note that the package does not contain any architecture specific files anymore and therefore the Architecture is set to all, even if it was any before.

If you set the section of the dummy package to oldlibs, tools like deborphan will suggest removal of the package once there aren't any more reverse-dependencies installed. All transitional, including non-library, packages should be put in this section, even though it's pretty much a misnomer, but there is currently no better section for this (see https://lintian.debian.org/tags/transitional-package-should-be-oldlibs-optional.html).

The new package is defined like this:

 Package: newname
 Replaces: oldname (<< 2.0-1~)
 Breaks: oldname (<< 2.0-1~)

You can also add a versioned Provides: entry if it is appropriate (for example when all interfaces are provided), which will help to satisfy any versioned reverse dependencies, and will allow users to remove the transitional package.

Please make sure that you use the proper version to break against. You must make sure that you break against all versions which still have the files in the old package. Especially if you split it between two Debian revisions, you must add a Debian revision and not only conflict against older upstream versions. (Or you will stumble across bugs like #397993).

Rationale: from "conflicts-with-version" Lintian tag: breaks is a weaker requirement that provides the package manager more leeway to find a valid upgrade path. Conflicts should only be used if two packages can never be unpacked at the same time, or for some situations involving virtual packages (where a version clause is not appropriate). In particular, when moving files between packages, use Breaks plus Replaces, not Conflicts plus Replaces.

If your new package also changes some filename-based interfaces to users or other packages, for example the package name changed because the program name changed, you might want to add compatibility symlinks. Those can either be placed in the old or the new package. If the symlink is there to stay, place it in the new package (so users can remove the transitional package and still have it). If the symlink is supposed to go away, placing it in the old package has the advantage that users can choose to have it or not (of course make sure to give the old package a proper description stating that it contains that compatibility) and that there is an easy way to see which other packages still need to change (things depending on the old name may need the compatibility symlink, while things depending on the new name must call it with the new name). As packages that have been in a release will need to have the transitional package in the next release, that extra information is especially useful if the package never released so the transitional package can be removed soon or if there are chances the transition to the new name will take more than one release to have all reverse-dependencies fixed).

Clean slate method

This method consists in switching to the new name without using a transitional package. It can imply renaming the binary package within the existing source (and possibly renaming the source package) or creating a new source package (which would require a request removal of the old source package). And let the new package Provides, Replaces and Conflicts the old package, ideally by using versioned Provides to fulfill versioned dependencies when targeting >= Debian Stretch.

This should be used for example for any non-leaf packages that are only ever installed by other packages depending on it. Because in that case the only thing needed will be for the reverse-dependencies to start depending on the new package.

But this method has disadvantages:

Disappearing package method

This page used to describe a method trying to get rid of the transitional package automatically by removing all it files. If you are interested why this does not work at all (yet?), take a look at the history of this page.

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