debtree — package dependency graphs on steroids

Introduction

This started with the simple question "how exactly does package X pull in package Y when I install it". The only way I knew of was to use aptitude interactively and just guess which package was the most likely culprit.

So I set out to create a simple script to recurse through dependencies...

Basically this meant building a dependency tree. I'd long wanted to play with dot, and this seemed like a good opportunity as visualizing the trees looked like a nice way to check their correctness.

To make a long story short, after the basic functionality had been implemented, it turned out to be fairly easy (and irresistible) to extend the functionality bit by bit.

So now we have a script that can generate dependency graphs in the form of .dot files that serve as input for dot (from the graphviz package).

The commands apt-cache and apt-rdepends have similar options, but debtree is a lot more powerful.

Examples

The examples below show the different levels of detail that can be obtained using debtree and explain the graphs. Please view them in the indicated order.

Note that Postscript viewers may not display some of the larger graphs until you zoom out one or more times. I've used kghostview and that at least always showed the thumbnail correctly.

• debconf
• aptitude
• advanced usage

Other packages for which (mostly default) graphs have been produced, roughly in ascending order of complexity:
bind9, debmirror, gettext, iceweasel, logcheck, logrotate, mutt, mysql-client, mysql-server, ssh, subversion, debiandoc-sgml, exim4, cupsys, gimp, lintian, apache2, wesnoth, vlc.

To get usable graphs for some of these, a number of packages have been added to the /etc/debtree/endlist configuration file. If you try other packages, you may need to do the same. Try to add only packages for which it is "logical" not to expand the graph any further.

Another option is to limit the number of dependency levels (the "depth" of the graph) by specifying a maximum depth or to reduce the amount of information included in the graph using the available command line options.

Download

The debtree package is available from the Debian archive for 'Sqeeze' and later. The package for 'Squeeze' can be installed without any problems on systems running 'Lenny'.

You can also check out the source code from the git repository using:
$ git clone git://git.debian.org/collab-maint/debtree.git

The dependencies are perl, libapt-pkg-perl, dctrl-tools and ucf; graphviz is recommended.

Comments to: Frans Pop. Please submit bugs and patches via the Debian Bug Tracking System.

Note
The option to print dependency paths has been dropped in version 0.9.0. I doubt anybody used that, and the same is possible using 'aptitude why', which does a better job.

Known issues

• In some cases graphs can get fairly messy when there are alternatives that have very similar dependencies. Good examples are apache and wesnoth (although the last looks to have been cleaned up in Squeeze).

Future development

There is still a lot of improvement possible. See also the comments in the current script.

• Option to generate sub-graphs on separate pages.
• Accept multiple packages as input to generate combined graphs.
• Have the tool automatically determine points where to stop recursing or where to create sub-graphs on a separate page.
• Maybe show aggregated package sizes.

$ debtree dpkg

Usage

See the debtree(1) man page for detailed usage information.

Examples

• Create a .dot file
  $ debtree --with-suggests <package> >out.dot
• Create a graph (PNG) from a .dot file
  $ dot -T png -o out.png out.dot
• Create a graph (Postscript) and view it using kghostview
  $ debtree <package> | dot -Tps | kghostview - &

Option summary

--show-installed | -I

Show which packages are installed on the system

--show-rdeps | -R

Also show reverse dependencies of the package and any virtual packages it provides

--build-dep | -b

Generate a graph showing build dependencies instead of package dependencies

--arch=<arch>

Specify the architecture (or 'all') for the build dependency graph (default is the architecture of the system)

--with-suggests | -S

Include suggested packages; dependencies of suggested packages are never included

--no-recommends

Don't show recommended packages

--no-alternatives

Only show the first dependency from a set of alternatives (i.e. show what would be installed by default)

--no-provides

Do not show virtual packages provided by the requested package

--max-providers=<num>

Limit the display of packages that provide a virtual package (default: 3)

--no-versions

Don't show the versions for versioned dependencies

--no-conflicts

Don't show unversioned conflicts

--versioned-conflicts | -VC

Include versioned conflicts; by default only unversioned conflicts are shown

--max-depth=<num>

Limit the number of levels of dependencies

--rdeps-depth=<num>

The maximum number of levels for reverse dependencies (default: 1)

--max-rdeps=<num>

Limit the display of indirect reverse dependencies (default: 5)

--no-skip

Also display packages that are suppressed by default (e.g. libc6)

--show-all

Generate full dependency tree (recurse for all packages); implies --no-skip

--rotate | -r

Draw the graph top-town instead of left-to-right

--condense

Condense the graph by merging lines (relationships) between packages

--quiet | -q

Suppress any informational/warning messages

--verbose | -v

Increase verbosity to display debug messages; can be repeated

Configuration

/etc/debtree/skiplist

Packages that by default will be excluded from dependency graphs.

/etc/debtree/endlist

Packages for which by default no dependencies will be shown on graphs.

See the comments in these files and the examples on these pages for information on how they are used. The configuration can be overruled on a per-user basis by creating a directory ~/.debtree/ and adding custom versions of these files there.

Suggestions for packages to add are welcome. Please mail both the command for the graph you'd like to reduce and the packages you're proposing to add to the lists.

The current list of 'skip' packages is:
libc6, libgcc1, libstdc++6, zlib1g, libx11-6, libc6-dev, libc-dev.
Reason these packages are excluded is that they are so common that including them only result in cluttering the graph without adding any real information. An option is available that allows to generate a full graph that includes these packages.

Tips

The graphviz suite includes utilities that can be used to manipulate graphs after they have been generated. See for example the man pages for prune and gvpr.