For a specific package, can I find out why it is installed?
So, can I see or it's manually installed, or that it is installed as a dependency of another package? Or that it is installed as part of the distro?
A quick solution is to enter the following command in a terminal:
aptitude why $package
or, if you are only interested in the ultimate cause:
aptitude why $package --show-summary
Replace $package with the package's name, and you may need to install the
aptitude package first.
Here is output you might get for
aptitude why aspell --show-summary
Packages requiring aspell: inkscape
For more detail you would run
aptitude why aspell. You can read the example output, below, as follows: "You manually installed
inkscape, which requires
libgtkspell, which requires
libenchantic2a, which requires
i markers indicate installed packages;
A markers indicate automatically installed packages.)
i inkscape Depends libgtkspell0 (>= 2.0.10) i A libgtkspell0 Depends libenchant1c2a (>= 1.6.0) i A libenchant1c2a Depends aspell-en | myspell-dictionary | aspell-dictionary | ispell-dictionary | hunspell-dictionary i A aspell-en Depends aspell (>= 0.60.3-2)
Finally, the following command
apt-cache rdepends --installed $package
lists the other packages installed on your computer that depend directly on $package. You can add the
--recurse option to list all packages that depend directly or indirectly on it.
A quick and short reasoning on why a certain package was installed can be found out by typing the following command in a terminal (
Applications -> Accessories -> Terminal) :
aptitude why <package-name>
Replace with the name of the package you are interested in. For example, typing
aptitude why libgoo-canvas-perl outputs the following :
i shutter Suggests libgoo-canvas-perl
This basically means that the package
shutter in this case has suggested
libgoo-canvas-perl be installed. By then typing
aptitude why shutter I can walk up the dependency chain.
However, there is a caveat. I often notice aptitude finds the most plausible explanation for the situation that may not be the actual case, but will nevertheless give you a clue to look further.
In my case,
libgoo-canvas-perl - however, suggested packages are not automatically installed by default. Nevertheless, it jogs my memory of the "experience" with not being able to edit screenshots with
shutter which led me to manually install
Finally, you can find out whether a package was installed automatically (meaning decided by the package management system as mandatory from looking at dependencies and recommendations of other packages you asked it to install) by running following command.
aptitude show <package-name>
This will output a line like below (3rd line of the output) :
Automatically installed: no
For more info run
info aptitude (in a terminal) or visit the Aptitude wiki page
To find out when a particular package was installed, there are 2 options:
Install(mind the case) to list all entries regarding installation. However, this will only show the packages installed using Synaptic
Run the following command in a terminal. This will search dpkg logs for installation history entries. However, there is maximum limit of how much of these logs are retained, so if the package you are looking for was installed a long time ago, you may not find it. More details here
zcat -f /var/log/dpkg.log* | grep "\ install\ " | grep -i <package-name>
Yes, you can, and it's a pretty obvious command, in fact. Assuming you've aptitude installed, you can open up a Terminal Window ad type:
aptitude why package
That should give a list of packages that depend on that specific package. If it's a manually installed package, it will say something like "It wasn't possible to find a reason to install package".
Here's a simple way that doesn't rely on
aptitude, which 10.10 doesn't ship by default anymore.
Open Synaptic and try to remove it.
If a dialog pops up asking you to delete other packages, those are the packages that (recursively) depend upon it.
apt-get remove package_name_goes_here -s
Again, the packages that would be removed as a result are all those that (recursively) depend on it. (The
-s parameter tells
apt-get to not actually remove the package.)