How to List Installed Packages in Debian 12 Bookworm System

Debian 12, codenamed “Bookworm,” is a robust and stable Linux distribution widely used for servers and desktops. As a Debian user or system administrator, managing installed packages is crucial for system maintenance, troubleshooting, and auditing. In this guide, we will explore different methods to list installed packages on Debian 12 Bookworm.

Why List Installed Packages?

Knowing what packages are installed on your system is useful for several reasons:

• System Auditing: Check which software is installed for security and compliance.
• Dependency Management: Identify dependencies when installing or removing software.
• System Migration & Backup: Reinstall the same set of packages on a new system.
• Troubleshooting: Diagnose conflicts or missing packages.

Now, let’s explore various methods to list installed packages in Debian 12.

1. Using dpkg Command

dpkg (Debian Package Manager) is a low-level package management tool in Debian-based systems.

Listing All Installed Packages

To display all installed packages, run:

 dpkg --get-selections

This will output a list of all installed packages along with their statuses (e.g., installed, deinstall, purge).

Filtering Specific Packages

To check if a specific package is installed, use grep:

dpkg --get-selections | grep <package-name>

For example, to check if nginx is installed:

dpkg --get-selections | grep nginx

Displaying Detailed Package Information

For a more detailed view of a package, use:

dpkg -l | grep <package-name>

Or list all installed packages in a tabular format:

dpkg -l

The output includes:

• Desired state (ii: installed, rc: removed but config files remain, etc.)
• Package name
• Version
• Architecture
• Description

2. Using apt Command

The apt (Advanced Package Tool) command-line utility is commonly used for package management.

Listing All Installed Packages

To list all installed packages:

apt list --installed

This command provides a list of installed packages, including their versions and architectures.

Searching for a Specific Package

To find if a specific package is installed, use:

apt list --installed | grep <package-name>

For example, to check if curl is installed:

apt list --installed | grep curl

3. Using dpkg-query Command

The dpkg-query command provides another way to query installed packages.

List All Installed Packages

Run the following command:

dpkg-query -l

This works similarly to dpkg -l, displaying package names, versions, and descriptions.

Get Package Details

To get detailed information about a specific package:

dpkg-query -W -f='${binary:Package} ${Version}\n' <package-name>

For example:

dpkg-query -W -f='${binary:Package} ${Version}\n' openssh-server

This outputs the package name and its version.

4. Using apt-mark Command

The apt-mark command helps check manually installed packages.

List All Manually Installed Packages

apt-mark showmanual

This displays packages explicitly installed by the user.

List Packages Installed as Dependencies

To see packages installed as dependencies (automatically installed):

apt-mark showauto

5. Using snap Command (For Snap Packages)

Snap packages are not managed by apt or dpkg. To list installed Snap packages:

snap list

This shows all Snap-installed applications with their versions.

6. Using flatpak Command (For Flatpak Packages)

If your system uses Flatpak, list installed Flatpak applications with:

flatpak list

This displays installed Flatpak applications with details.

7. Exporting Installed Package List

For backup or migration, save the installed package list and restore it later.

Save Installed Packages to a File

dpkg --get-selections > installed-packages.txt

To restore packages on a new system:

dpkg --set-selections < installed-packages.txt
apt-get dselect-upgrade

For apt:

apt list --installed > installed-packages.txt

Conclusion

Managing installed packages in Debian 12 Bookworm is essential for system administration, troubleshooting, and migration. This guide covered multiple methods:

• dpkg for basic listing.
• apt for detailed package management.
• dpkg-query for formatted queries.
• apt-mark for tracking user-installed packages.
• snap and flatpak for non-standard package managers.

By mastering these commands, you can efficiently monitor and manage software installations on your Debian 12 system. Whether you’re auditing, troubleshooting, or migrating, knowing how to list installed packages will be a valuable skill.