dpkg-reconfigure

The dpkg-reconfigure command is a powerful tool in Debian-based Linux distributions, including Ubuntu, that allows you to reconfigure an already installed package. This command re-runs the configuration process for a package, allowing you to change settings and options that were selected during the initial installation.

Basic Usage

The basic syntax for dpkg-reconfigure is:

sudo dpkg-reconfigure [options] package_name

• package_name: The name of the package you want to reconfigure.

Example Usage

Reconfiguring a Package

For example, to reconfigure the tzdata package (which sets the system timezone), you would use:

sudo dpkg-reconfigure tzdata

This command will bring up the configuration dialog for tzdata, allowing you to select a new timezone.

Options

dpkg-reconfigure supports several options to control its behavior:

• -a: Reconfigure all installed packages.

• -f: Specify the frontend to use (e.g., dialog, readline, noninteractive).

• -p: Set the priority of questions to be asked (e.g., low, medium, high, critical).

• -u: Use debconf database values without prompting.

• --default-priority: Use the default priority for questions.

Frontends

You can specify the frontend that dpkg-reconfigure should use to interact with you during the reconfiguration process. The most common frontends are:

• dialog: Provides a text-based user interface.

• readline: Provides a command-line interface.

• noninteractive: Runs without user interaction, using default values or pre-configured settings.

To specify a frontend, use the -f option:

sudo dpkg-reconfigure -f readline package_name

Priorities

You can control which questions are asked during reconfiguration by setting the priority level with the -p option. The priority levels are:

• low: Ask all questions.

• medium: Ask only medium and higher priority questions.

• high: Ask only high and critical priority questions.

• critical: Ask only critical questions.

To set the priority level, use the -p option:

sudo dpkg-reconfigure -p high package_name

Common Use Cases

Changing Keyboard Layout

To reconfigure the keyboard layout, you can reconfigure the keyboard-configuration package:

sudo dpkg-reconfigure keyboard-configuration

Reconfiguring Display Manager

If you have multiple display managers installed (e.g., gdm3, lightdm, sddm), you can reconfigure the display manager selection:

sudo dpkg-reconfigure lightdm

Updating Postfix Configuration

To update the configuration of the Postfix mail server:

sudo dpkg-reconfigure postfix

Conclusion

The dpkg-reconfigure command is an essential tool for managing the configuration of installed packages on Debian-based systems. It provides a way to revisit and modify package settings without reinstalling the package. By understanding how to use dpkg-reconfigure, you can efficiently manage your system's configuration and adapt it to your needs.