396

In order to research what caused the installation of a given package, I'd like to get a list of packages which depend on that package. I couldn't find anything obvious in man dpkg.

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  • Related: askubuntu.com/questions/13296/…
    – Seth
    Commented Feb 26, 2015 at 3:58
  • 16
    The older question's answers all revolve around aptitude, something that hasn't been installed by default for years. In 2017, everyone on Ubuntu still has apt-cache. Anyone who follows the linked question is going to get lost in a discussion about a program few will have.
    – Lambart
    Commented Aug 18, 2017 at 17:48

8 Answers 8

488

apt-cache rdepends packagename should do what you want.

To limit it to packages that are installed on your system: apt-cache rdepends --installed packagename

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  • 3
    Excellent! apt-cache rdepends tofrodos confirmed the suspicion that it was installed by another package (the obsoleted dos2unix).
    – l0b0
    Commented Apr 30, 2012 at 13:12
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    As for today (apt version 0.9.9.1), there is --recurse option that works with rdepends.
    – jarno
    Commented Dec 22, 2013 at 14:00
  • 96
    If you add --installed, the output is even useful for packages which can be used by many others: apt-cache rdepends --installed packagename
    – quazgar
    Commented May 27, 2014 at 22:08
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    There's a slightly different syntax which helped me to differentiate between Recommends, Depends, Suggests, etc. Syntax is sudo apt rdepends packagename (Notice it is not using apt-cache but simply apt) Commented Nov 16, 2017 at 5:26
  • 7
    For the output, why do some of the packages have a vertical bar (pipe symbol) before them? Commented Nov 16, 2017 at 5:35
96

aptitude has a fairly nice way of handling this:

$ aptitude why bash
i   foomatic-filters PreDepends bash (>= 2.05)

By default, it only lists the "most installed, strongest, tightest, shortest" reason, but you can use aptitude -v why to make it output everything it finds.

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  • 7
    Seems like it considers only the installed packages, not everything available. And that was what I needed. Commented Jul 25, 2013 at 10:06
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    For that you want reverse-depends in ubuntu-dev-tools
    – tumbleweed
    Commented Jul 25, 2013 at 11:38
  • 1
    ubuntu-dev-tools is in Debian
    – tumbleweed
    Commented Jul 26, 2013 at 11:18
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    This is great. I learned that openssh-server recommended (and therefore installed) xauth on a headless server, dragging in hundreds of x11 dependencies and dozens of useless updates a month. That's the problem with automated package management!
    – BaseZen
    Commented Mar 2, 2018 at 3:17
  • 1
    Worth noting that the --recurse option is useful too. As in apt rdepends --recurse packagename Commented Nov 18, 2020 at 6:22
44

The simplest option is still:

apt rdepends package-name

which does not require you to install any package.

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  • 1
    What is this adding to the accepted answer?
    – l0b0
    Commented Nov 26, 2018 at 23:58
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    The accepted answer has nothing to do with this one. The output is completely different and way more useful for human consumption than apt-cache's. The answer mentions that apt-cache is not installed by default everywhere - that alone should be a rather good hint why this answer has its purpose. finally, this is actually the answer I was looking for, so any downvote is rather silly.
    – stefanct
    Commented Nov 28, 2018 at 13:21
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    One very significant reason why this is better than the accepted version is that it includes the version of the dependencies, unlike apt-caches output. It's exactly what I needed right now (debugging a glibc 2.28 incompatibility, so upvoting) Commented Jan 2, 2019 at 9:10
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    upvote for using just apt. at the time of the original answer, I'm not sure this just apt solution would have been valid, but if it is now, that's good. Commented Apr 20, 2019 at 11:53
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apt-cache showpkg <pkgname> 

Example:

apt-cache showpkg lightdm
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  • 5
    This is actually still the correct syntax for apt-cache. Just tried apt showpkg xorg and got E: Invalid operation showpkg
    – Terrance
    Commented Jun 8, 2020 at 14:13
  • This did the trick!!!
    – k.Cyborg
    Commented May 11, 2022 at 15:00
19

There is more than one way, with each method showing a different output.

For a detailed view of the full reverse dependency tree;

aptitude install apt-rdepends
apt-rdepends -r bash

Alternatively;

apt-cache showpkg bash

Or a concise list:

apt-cache rdepends bash
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  • What exactly does rdepends show in that tree? apt-rdepends php7.0-fpm shows sed. sed doesn't depend on PHP, let alone PHP FPM. Commented Jan 9, 2018 at 23:21
  • It is reverse depends, it means that PHP depends on sed. Commented Apr 25, 2018 at 3:30
  • 2
    Hi guys, actually "apt-rdepends" stands for "recursive dependency". If you want reverse recursive dependency, you have to type : apt-rdepends -r yourPackageNameHere
    – SebMa
    Commented Apr 27, 2018 at 12:56
  • The apt-cache man page says "rdepends shows a listing of each reverse dependency a package has". Whereas apt-rdepends requires the -r option to do reverse dependencies, as @SebMa says.
    – NeilG
    Commented Feb 5, 2019 at 3:16
18

In addition to other good answers, an apt/apt-get -s does a "simulated" removal (or install).

sudo apt -s remove <pkgname>

Using -s or --simulate to remove (or install) packages, will normally list any dependencies affected. It will show orphaned packages when removing, or needed dependencies when installing, without actually executing the install or remove. Informational only.

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  • apt remove -s php7.0-fpm shows The following additional packages will be installed: apache2 apache2-bin apache2-data libapache2-mod-php7.0 libaprutil1-dbd-sqlite3 libaprutil1-ldap liblua5.1-0. Why would apache get installed if I remove PHP FPM? Commented Jan 9, 2018 at 23:22
  • @DanDascalescu Hmm. Might be a bad install/remove script for apt pkg or might be you have some other dependencies that install apache2 as dep (meaning a webserver is needed - and I believe apache2 is default web server). Could be a few things. Just not sure. Has the smell of a good post on AskUbuntu if you haven't found an answer.
    – B. Shea
    Commented Jul 10, 2018 at 16:26
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With the reverse-depends command from the package: ubuntu-dev-tools

reverse-depends libjs-openlayers
# For build depends search
reverse-depends -b libjs-openlayers
Reverse-Recommends
* gis-osm

Reverse-Depends
* cyclograph
* phpmyadmin
* sumo-tools

Packages without architectures listed are reverse-dependencies in: amd64, arm64, armhf, i386, ppc64el, s390x
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Since the --installed option of apt-cache was mentioned in comments of RobotHumans's answer and does not make much sense as the matching is done against all versions, including uninstalled ones (see Debian bug 1029586), here's the solution proposed by Julian Andres Klode to get the reverse dependencies among the installed packages:

apt list '?any-version(?installed?depends(?exact-name(packagename)))'

Note that packagename is just the package name, without architecture information. For instance, libpcre3 works, but not libpcre3:amd64.

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