How to Reconfigure Installed Package in Ubuntu and Debian?

Ubuntu and Debian users can easily modify or restore the configuration settings of an installed package with the dpkg-reconfigure command. This command works in tandem with debconf, the configuration system for Debian packages, and allows users to retrieve settings, modify configurations, and troubleshoot issues. By answering a series of configuration questions similar to those presented during installation, users can change the settings of a package without uninstalling and reinstalling it.

Viewing Current Package Configuration

The debconf-show command allows you to view the current configuration settings of any installed package. This is useful for troubleshooting or understanding how a package is currently configured before making changes.

$ sudo debconf-show phpmyadmin

* phpmyadmin/dbconfig-install: boolean true
* phpmyadmin/reconfigure-webserver: boolean true
* phpmyadmin/dbconfig-upgrade: boolean true
* phpmyadmin/mysql/admin-pass: password [hidden]
* phpmyadmin/mysql/app-pass: password [hidden]
* phpmyadmin/app-password-confirm: password [hidden]
* phpmyadmin/password-confirm: password [hidden]
* phpmyadmin/db/app-user: string phpmyadmin
* phpmyadmin/db/dbname: string phpmyadmin
* phpmyadmin/dbconfig-remove: boolean false
* phpmyadmin/remote/host: string
* phpmyadmin/upgrade-backup: boolean true
* phpmyadmin/db/basepath: string
* phpmyadmin/internal/skip-preseed: boolean false
* phpmyadmin/install-error: select
* phpmyadmin/dbconfig-common: boolean true
* phpmyadmin/missing-db-package-error: select

Reconfiguring Installed Packages

The dpkg-reconfigure command allows you to modify package configuration settings through an interactive interface. This saves time and effort while minimizing the risk of data loss compared to uninstalling and reinstalling packages.

$ sudo dpkg-reconfigure phpmyadmin

The command will present an interactive dialog where you can modify various settings

Please select the web server that should be automatically configured to run phpMyAdmin:

    1. Apache2
    2. Nginx
    3. Lighttpd
    4. None

Select the web server to reconfigure: 1

Configuring phpMyAdmin for Apache2...

Please enter the MySQL application password for phpmyadmin:

Configure database for phpmyadmin with dbconfig-common? Yes / No: Yes

Please enter the password that will be used for the phpmyadmin database:

Creating a phpmyadmin database...
Configuring database...
Setting up phpmyadmin...

phpMyAdmin has been installed and configured successfully.

Customizing Reconfiguration Behavior

Using Different Frontend Interfaces

You can specify which frontend interface to use during reconfiguration with the -f flag. Available options include dialog, readline, and noninteractive.

$ sudo dpkg-reconfigure -f readline phpmyadmin

Creating config file /etc/phpmyadmin/config-db.php with new version
chown: changing ownership of '/var/lib/phpmyadmin/tmp': Operation not permitted
chown: changing ownership of '/var/lib/phpmyadmin/session': Operation not permitted
Reloading web server config: apache2.

Setting Question Priority Levels

Use the -p option to set a minimum priority level for configuration questions. Only questions at or above the specified priority will be asked. Priority levels include low, medium, high, and critical.

$ sudo dpkg-reconfigure -p critical phpmyadmin

Configuring phpmyadmin package with critical priority...
debconf: unable to initialize frontend: Dialog
debconf: (Dialog frontend requires a screen at least 13 lines tall and 31 columns wide.)
debconf: falling back to frontend: Readline

Configuring Debconf Defaults

To permanently change the default frontend or priority settings for all package configurations, reconfigure the debconf package itself

$ sudo dpkg-reconfigure debconf

Common Use Cases

Accessing Manual Documentation

For comprehensive information about all available options and examples, consult the manual page

$ man dpkg-reconfigure

The manual page provides detailed documentation on command usage, available frontends, priority levels, and practical examples for system administrators.

Conclusion

The dpkg-reconfigure command is an essential tool for Ubuntu and Debian system administration, allowing efficient modification of package configurations without reinstallation. Combined with debconf-show for viewing current settings and various customization options, it provides flexible package management capabilities for both interactive and automated environments.