debconfsetselections

debconf-set-selections is a command-line utility from the debconf package used on Debian-based systems to pre-seed answers to debconf prompts during package configuration. By populating the debconf database with predefined responses, it enables automated or non-interactive installations and upgrades.

Format and types: The tool reads lines in the form: package-name question-name type value. Common types include boolean, string, password, select, and multiselect. Examples:

- mysql-server mysql-server/root_password password my-secret-pw

- mysql-server mysql-server/root_password_again password my-secret-pw

- postfix postfix/main_mailer_type select Internet Site

- some-package some-feature/enable boolean true

Usage: Input can be provided directly from a file or here-document. For example:

debconf-set-selections < preseed.txt

or

debconf-set-selections << 'EOF'

package-name question-name type value

EOF

Application: Debconf-set-selections is typically used in automated deployment workflows. When used in conjunction with non-interactive installations (for example, with DEBIAN_FRONTEND=noninteractive and apt/dpkg), it ensures that prompts receive predefined answers and do not halt installation.

Notes: The command updates the debconf database, and later installations will use the supplied values if they correspond to the respective templates. If a template is not relevant to a given package, it will be ignored. To modify configurations after installation, you can use dpkg-reconfigure or related debconf tools. For viewing current preseeded values, there is a separate utility debconf-get-selections.