Package Management – How to List Dependent Packages (Reverse Dependencies)

You can use either of these two one-liners. Both yield the exact same output on my machine and are more precise than all solutions proposed up until now (July 6, 2014) in this question.

Using apt-mark:

comm -23 <(apt-mark showmanual | sort -u) <(gzip -dc /var/log/installer/initial-status.gz | sed -n 's/^Package: //p' | sort -u)

Using aptitude:

comm -23 <(aptitude search '~i !~M' -F '%p' | sed "s/ *$//" | sort -u) <(gzip -dc /var/log/installer/initial-status.gz | sed -n 's/^Package: //p' | sort -u)

Very few packages still fall through the cracks, although I suspect these are actually installed by the user, either right after the installation through the language localization setup or e.g. through the Totem codec installer. Also, the linux-header versions also seem to accumulate, even though I've only installed the non version-specific metapackage. Examples:

libreoffice-help-en-gb
openoffice.org-hyphenation
gstreamer0.10-fluendo-mp3
linux-headers-3.13.0-29    

How does it work:

1. Get the list of manually installed packages. For aptitude, the additional sed strips out remaining whitespace at the end of the line.
2. Get the list of packages installed right after a fresh install.
3. Compare the files, only output the lines in file 1 that are not present in file 2.

Other possibilities don't work as well:

• Using the ubuntu-14.04-desktop-amd64.manifest file (here for Ubuntu 14.04) instead of /var/log/installer/initial-status.gz. More packages are shown as manually installed even though they are not.
• Using apt-mark showauto instead of /var/log/installer/initial-status.gz. apt-mark for example doesn't include the xserver-xorg package, while the other file does.

I used various other StackExchange posts as references, however none work as well as the above solution:

• aptitude + manifest
• initial-status.gz + apt-mark showauto

Both list more packages than the above solution.

EDIT: What to do if you've upgraded from a previous release:

If you've upgraded Ubuntu from one release to the next, you will probably need to adjust this process. In that case, I would check the manifest file of the newer release (see above) in addition to the initial-status.gz file from the current release. You can easily do that by just adding another comparison. Using just the manifest file will not work, as the manifest file unfortunately does not contain everything that the initial_status.gz file does (I checked).

I created a script that does exactly what you want: https://gist.github.com/kotarou3/2b311fb7b79ae6b682246b32acf0b7e9

python3-apt and python3-networkx are the dependencies. It uses the apt package cache as the source of package information.

Package names themselves are output one per line to stdout, while any comments about them (such as if they are part of a cycle) are to stderr

Example:

$ ./find-top-level-packages.py nginx nginx-core zlib1g firefox
firefox
nginx
$ ./find-top-level-package.py -h
usage: find-top-level-packages.py [-h] [--root-dir dir]
                                  [--follow-unspecified-packages]
                                  [--no-use-recommends]
                                  [--show-missing-recommends]
                                  [package [package ...]]

Find top-level packages of the dependency graph

positional arguments:
  package               package names to use (default: all installed packages)

optional arguments:
  -h, --help            show this help message and exit
  --root-dir dir        act as if chrooted in the specified directory
  --follow-unspecified-packages
                        follow dependencies of packages not part of the
                        initial input
  --no-use-recommends   don't use recommended packages for the dependency
                        graph
  --show-missing-recommends
                        list missing recommended packages suffixed with a dash