How do I check if a package is installed on my server?

Question

I recently installed Ubuntu Server edition 13.10 (Saucy Salamander). But I have run into a bit of problem.

At the end of the installation, it asks about several extra packages whether you want them or not, like OpenSSH server and virtual machine host. Here's what I'm looking at:

Now, my problem is that I can't remember if I have checked the "virtual machine host" checkbox. How do I check if my server has the corresponding packages?

What packages come with the virtual machine host?

Solution 1

Are you looking to know about all dpkg commands with options? Have a read from the below link.

15 dpkg commands to Manage Debian based Linux Servers

To List all Installed Packages

Here less is a simple text reader used to scroll through the list of packages in a new buffer that opens in the existing terminal window. The list will not be mixed with other terminal commands and output. Hit q to return to the terminal prompt. See man less for more info.

dpkg -l | less

To check whether a package is installed or not:

dpkg -l {package_name}
dpkg -l vlc

To check if the package is installed or not (for example, vlc). If installed, launch the package:

dpkg -l | grep vlc

Show the location where the package is installed. The -S (capital S) stands for "search"

sudo dpkg -S {package_name}
sudo dpkg -S skype

To use Grep to search:

dpkg -l | grep {keywords}
dpkg -l | grep pdf

Solution 2

apt -qq list PACKAGE can also be used for checking whether the PACKAGE is installed.

If installed it'll print something like (with [installed] at the end of the line):

$ apt -qq list awscli
awscli/stable,now 1.4.2-1 all [installed]

If not installed the output will be:

$ apt -qq list awscli
awscli/stable 1.4.2-1 all

Solution 3

Use dpkg

This command is the Debian package manager.

You can list all the installed packages with

dpkg -l

You can see details for a specific package with

dpkg -p packagename

And to learn if it is installed, use

dpkg -s packagename | grep Status

You can learn which package contains the software you want with

apt-cache search name*  

In your case you should use this command to search the package name you want

apt-cache search virtual machine host 

Solution 4

I've found a way to check for package installation with just dpkg-query command and no pipes.

I searched for such solution while writing a task for ansible playbook.

You can do something like this:

/usr/bin/dpkg-query --show --showformat='${db:Status-Status}\n' '<your package name>'

This is just one another way to do the thing.

Solution 5

Simpler solution:

There is now an apt list command that lists available packages, and the --installed command will show only installed packages. You can also search for a specific package with

apt list <package>

Or to see only the matching installed packages

apt list <package> --installed

There are also the --upgradeable and --all-versions flags.

If you do not know the exact package name, you can use apt search followed by part of it to see a list of related packages. This will allow you to use a partial name or regex term(s) to filter a list of available packages, but it does not have the nifty flags for filtering that apt list has.

Also see man apt for more information.

View more solutions

Comments

[Daniel]

$ apt-cache policy <package-name>, e.g. $ apt-cache policy dillo

[D.Zou]

thanks for telling me the name of the task, that was one of my problems, wasn't sure which package to look for.

[heypaleblue]

What is the diference between this and dpkg-query -l "packagename"

[Brannon]

You can put a star on the end of the package name for a wildcard.

[Viktor Benei]

Do not depend on the exit code of dpkg -l packagename, as it might return with a 0 exit code even if the package is not fully installed - see: github.com/bitrise-io/bitrise/issues/433

[Gopal Venu]

dpkg -l | cut -d " " -f 3 | grep "^vlc" to show all package names that start with vlc

[sjas]

pipes in ansible can be used with the shell module.

[mtalexan]

FYI, this doesn't work for meta packages since they don't correlate directly to a dpkg. Your response does answer the question as asked though.

[mtalexan]

You can also use the --installed option for that command to limit to matches which are actually installed.

[Gabriel Staples]

What's the -qq for? It seems to work identically without it, and that option isn't in the manual man apt

[Lupen]

@GabrielStaples It looks like the apt list command isn't yet fully documented. Some quick testing on 16.04 seems to indicate that -q is a synonym for --quiet option. The first -q prevents the word "Done" being printed. The second also prevents "Listing... " from being printed.

[Franklin Yu]

Even on Bionic, apt list still seems to be "WIP". Anyway for interactive use it does the job. I think in general apt family isn't meant for scripting, in which case you would still want dpkg.

[Franklin Yu]

This has been mentioned by Victor two years ago.

[Franklin Yu]

@heypaleblue They are the same. From manual page: "dpkg can also be used as a front-end to dpkg-deb(1) and dpkg-query(1). The list of supported actions can be found later on in the ACTIONS section. If any such action is encountered dpkg just runs dpkg-deb or dpkg-query with the parameters given to it..."

[Rockallite]

Also apt-cache show <pkg_name> to show detailed information about installed and installable versions of a package.

[Smar]

apt shouldn’t be used in scripts, the command always says.

[Manuel Jordan]

Really is apt list --installed | grep <package>, the --installed part is mandatory

[sk8forether]

@ManuelJordan Yes and no. Technically the --installed is needed to see only installed packages (I've updated my post to make this clearer), but the grep is excessive since you can specify the package to the command directly.

[Manuel Jordan]

Agree, 'grep' is a secondary filter .... would be nice indicate the explicit difference between list and search ...

[sk8forether]

@ManuelJordan Added :-)

[Manuel Jordan]

Is interesting how these two options "search" and "list" are not merged in one command, something like list --remote (same as search to search in the repositories and without matter if the <package> is complete or not) and list --install (to search in the local computer) all the currently installed

[Marinos An]

What the answer does not mention is: which output of dpkg -l {package_name} would inform that the package is installed?

[Treviño]

While this is fine for informative version its return value isn't indicative

[vkozyrev]

This is the most elegant way to check

[js.mouret]

careful as this will not work if the package was previously installed then removed.

[Ciro Santilli OurBigBook.com]

@js.mouret yes, updated.

[josch]

@MarinosAn The first column of the dpkg -l output has to say ii for the package to be installed. If it says anything else (like rc) then it is not fully installed.

[josch]

How can an answer that suggests using dpkg -l to check whether a package is installed get over 300 upvotes without explaining which part of the output actually tells the user whether a package is installed or not? Please annotate your answer to explain that the first column of dpkg -l has to say ii or otherwise the package is not installed.

[josch]

This will be wrong for packages that have the string installed anywhere in their description. For example try running dpkg -s debsums | grep installed.

[Marinos An]

@josch Thank you! Created an answer based on your feedback.

[josch]

"Now in case it is not installed at all, dpkg by default prints an error" this is still not true. dpkg -l lists packages that once were installed but are not installed now without an error. Also, if you start using this in a shell pipeline, dpkg -l is not the command you want to use. You want to use dpkg-query --show --showformat='${db:Status-Status}\n' or similar but not dpkg -l which produces output meant for human consumption and not scripts. The output format could change in the future and then your script breaks.

[Marinos An]

@josch "dpkg -l lists packages that once were installed but are not installed now without an error.": In that case I guess the line would not start with ii so && echo installed which is based only on grep exit code (false when no match) will not be executed. In any case as you correctly pointed out dpkg-query is better so I have updated my answer.

[josch]

Thanks. One thing is still wrong though. You write that dpkg uses dpkg-query. This is not true. Why do you write down things if you don't know whether they are true or not?

[Marinos An]

@josch You are right. I misinterpreted the manpage which says: "dpkg can also be used as a front-end to dpkg-deb(1) and dpkg-query(1)". My bad, I updated.

[Admin]

CLI warning: apt does not have a stable CLI interface. Use with caution in scripts