debconf-show

debconf-show [options] [package ...]

--install-size
    Shows the approximate disk space occupied by the specified packages, as reported by debconf.

--help
    Displays a help message and exits.

--version
    Shows version information and exits.

--root=DIR
    Use an alternative root directory for accessing the debconf database. Useful when working with chroot environments.

package ...
    One or more package names for which debconf questions and values should be displayed. If omitted, questions for all configured packages are shown.

debconf-show is a utility within the Debian configuration management system, debconf. It allows users to inspect the current values of questions stored in the debconf database. This database holds configuration settings for various installed packages, which are typically set during package installation, upgrade, or re-configuration via dpkg-reconfigure.

The primary purpose of debconf-show is to provide a snapshot of a package's configuration as seen by debconf. This is invaluable for debugging, auditing system configurations, or simply understanding what options have been chosen for a particular package. By default, it will list all questions and their corresponding values for specified packages. If no packages are given, it attempts to show questions for all installed packages that use debconf, though this can produce a very large output. The output includes the question name, type, and the current value.

It's a read-only tool, meaning it only displays existing values and does not allow modification of any settings. For interactive modification, dpkg-reconfigure should be used.

The output of debconf-show can be verbose, especially when no specific packages are named, as it attempts to list all questions for all installed packages. The raw format might not be directly suitable for programmatic parsing without careful filtering. It's important to remember that debconf-show displays the stored configuration values in the debconf database, which may not always reflect the currently active configuration of a service if a package's configuration files have been manually edited or if a service has not been restarted after a debconf update. Access to the debconf database typically requires appropriate user permissions, often root, depending on the system's configuration.

For each debconf question, debconf-show typically displays information in a format like:
* Question name (e.g., apache2/mpm_type)
* Question type (e.g., select, boolean, string, password)
* The current value stored for that question (e.g., prefork, true, /var/www/html).
It may also include the question's extended description or priority, depending on the debconf database content.

debconf-show is an indispensable tool for debugging package configuration issues. System administrators can quickly ascertain what choices were made during installation or re-configuration. In scripting, its output can be parsed (though with care due to its human-readable nature) to automate checks or to generate reports on system configurations across multiple machines.

The debconf configuration management system was introduced in Debian around the late 1990s/early 2000s, primarily to standardize and simplify the process of configuring packages during installation and upgrades. debconf-show emerged as a fundamental utility within this system, providing a crucial diagnostic and inspection tool from its early days. Its development has closely tracked the evolution of debconf itself, remaining a core component for administrators and developers to understand the state of package configurations without altering them.

debconf(7), dpkg-reconfigure(8), debconf-set-selections(1), debconf-communicate(1), debconf-get-selections(1)