How to find installed deb packages needlessly marked as manually installed

Question

Problem statement

apt and aptitude both remember which packages were installed automatically as dependencies of some other package or manually for some reason. For various reasons the list of manually packages may become needlessly large and can start to accumulate over time. These packages will be uninstalled only when specifically requested.

One common example are library packages which may be installed as hotfix for some reason, but later they could be marked as automatically installed once some software depending on them is installed. However, if that doesn't happen, they will remain installed even once the packages depending on them are uninstalled. Tools like deborphan may find these left-over packages in some cases, but they have to guess a lot and it's not a systemic solution.

Description of a possible solution

That's why I'm looking for a way to find such packages that can be marked as automatically installed without them resulting to be uninstalled. This would mean finding packages that are currently marked as manually installed, but are dependencies (or recommended dependencies) of some other installed package. These packages could then be marked as automatically installed and will be removed once they are not needed anymore by other software.

I think I might be able to make a tool like that with the Python bindings for libapt, but I would hate to reinvent the wheel if something like that already exists.

Answer 1

Search for packages that are manually installed, and that are a mandatory or recommended dependency of an installed package. Aptitude can do that.

aptitude search -q -F %p '?installed !?automatic (?reverse-depends(?installed .*) | ?reverse-recommends(?installed .*))'

I don't think there's a way to indicate what dependency was found for each package. If you want that information, Python would be the way to go. This very quick-and-dirty script seems to do it (mostly, I think it may be incorrect in some non-straightforward cases involving disjunctions, version dependencies, pre-depends, …).

#!/usr/bin/env python2
import apt

packages = apt.Cache()
covered = {}
# Inverse dependency computation: for each installed package, record which
# packages require it (as Depends: or Recommends:).
for p in packages:
    if p.installed:
        for l in p.installed.dependencies + p.installed.recommends:
            for d in l:
                if packages.has_key(d.name) and packages[d.name].installed:
                    if not covered.has_key(d.name):
                        covered[d.name] = []
                    covered[d.name] += [p.name]
# Print out the manually installed packages that are required by another
# installed package, as well as the requiring package(s).
for p in sorted(covered.keys()):
    if not packages[p].is_auto_installed:
        print(' '.join([p] + covered[p]))

Answer 2

apt package manager provides a straightforward way to find these packages usign apt-mark:

# apt-mark showmanual

This will show all packages marked as manually installed. You can change any of them to be auto using:

# apt-mark auto PACKAGE_NAME

From the apt-mark man page:

auto

auto is used to mark a package as being automatically installed, which will cause the package to be removed when no more manually installed packages depend on this package.

manual

manual is used to mark a package as being manually installed, which will prevent the package from being automatically removed if no other packages depend on it.

showauto

showauto is used to print a list of automatically installed packages with each package on a new line. All automatically installed packages will be listed if no package is given. If packages are given only those which are automatically installed will be shown.

showmanual

showmanual can be used in the same way as showauto except that it will print a list of manually installed packages instead.