How to List Installed Packages on Debian

Introduction

In this tutorial, you will see how to list and filter installed packages on Debian. We will also demonstrate how to count installed packages and determine a package's version. It also determines whether a given package is installed or not.

Knowing how to list installed packages can be useful when you need to install the same packages on a different machine. It's also helpful when you wish to reinstall your Debian-based system.

List Installed Packages with Apt

The package management system's command-line interface Apt combines the most useful features of apt-get and apt-cache.

Run the following command to list all packages that are currently installed on your system:

sudo apt list --installed

Output

adduser/stable,now 3.115 all [installed]
apt/stable,now 1.4.8 amd64 [installed]
apt-listchanges/stable,now 3.10 all [installed]
apt-utils/stable,now 1.4.8 amd64 [installed]
autoconf/stable,now 2.69-10 all [installed]
automake/stable,now 1:1.15-6 all [installed]
autotools-dev/stable,now 20161112.1 all [installed,automatic]
base-files/stable,now 9.9+deb9u5 amd64 [installed]
base-passwd/stable,now 3.5.43 amd64 [installed]
bash/stable,now 4.4-5 amd64 [installed]

A list of all installed packages, along with details on their versions and architecture, will be shown by the command. The output's right-most column indicates if the package was installed automatically as a dependency of another package.

It is a good idea to pipe the output to the less command to make it simpler to read because the packages list is lengthy:

sudo apt list --installed | less

Use the grep command to filter the results and see if a particular package is installed. As an illustration, you might type the following to check if the tmux package is installed on the system:

sudo apt list --installed | grep tmux

Output

tmux/stable,now 2.3-4 amd64 [installed]

As you can see in the output, you have tmux 2.3-4 installed on your system.

List Installed Packages with dpkg-query

The command line tool dpkg-query can be used to view details about packages listed in the dpkg database.

Type the following to receive a list of all installed packages:

sudo dpkg-query -l | less

A list of all installed packages, together with their versions, architecture, and a brief description, will be shown by the command.

The grep command can be used to filter the output of dpkg-query -l:

sudo dpkg-query -l | grep package_name_to_search

Create a List of all Installed Packages

When you run the following command, a file called packages_list.txt will be created on your Debian system with a list of all installed packages:

sudo dpkg-query -f '${binary:Package}\n' -W > packages_list.txt

With the list in hand, you can use the following methods to install the same packages on your new server:

sudo xargs -a packages_list.txt apt install

Count the Number of Installed Packages

You can use the same command for creating a packages list to determine how many packages are installed on your system. Instead of sending the output to a file, pipe it to the wc command to count the lines:

sudo dpkg-query -f '${binary:Package}\n' -W | wc -l

The number of installed packages will be shown in the output:

Output

466

Conclusion

You now understand how to list and filter installed packages on your Debian system.

If you have any queries, please leave a comment below and we’ll be happy to respond to them.