debconf-copydb

debconf-copydb [options] [sourcedb] [destdb]

--fromdb
    Specify the source database to copy from.

--todb
    Specify the destination database to copy to.

--type
    Set the database type (e.g., 'File', 'SQLite'). Default is 'File'.

--owner
    Set the owner for the destination file (for 'File' type databases).

--group
    Set the group for the destination file (for 'File' type databases).

--mode
    Set the file permissions for the destination file (for 'File' type databases).

--f
    Copy only specified fields (e.g., 'Value,seen').

--filter
    Copy only questions whose names match the regex.

--exclude
    Do not copy questions whose names match the regex.

--no-questions
    Do not copy questions, only configuration values.

--no-seen
    Do not copy the 'seen' flag for questions.

--set-seen
    Mark all copied questions as 'seen' in the destination.

--force
    Overwrite destination without prompting if it exists.

--dry-run
    Simulate the copy operation without making changes.

--verbose
    Provide detailed output during execution.

--help
    Display the help message.

--version
    Display version information.

debconf-copydb is a utility for copying configuration data between Debconf databases. It allows administrators to transfer values, seen flags, and other question properties from one Debconf backend to another, or to create backups. The command supports various database types, primarily 'File' (the classic text-based format) and 'SQLite'. It can copy a full database or selectively copy specific fields or questions based on regular expressions. This tool is invaluable for system migrations, debugging Debconf issues, or synchronizing configuration states across different environments or backup scenarios without reinstalling packages. It provides fine-grained control over what data is copied and how the destination database is handled.

debconf-copydb operates on the database files directly. Care should be taken when using it on an active system, especially with the primary Debconf database (typically /var/cache/debconf/config.dat), as concurrent writes might lead to inconsistencies. It's generally safer to perform operations on offline copies or during system maintenance windows.
The --owner, --group, and --mode options are only applicable when copying to 'File' type databases. They have no effect on 'SQLite' or other future database types.

The debconf system, including tools like debconf-copydb, has been a core component of Debian-based systems for managing package configuration since its introduction. debconf-copydb specifically addresses the need for flexible management of this configuration data, especially as different backend storage types (like SQLite) were introduced to offer more robust or performant alternatives to the traditional text-based File format. Its development has focused on providing granular control over what data is copied and how it's handled, reflecting various use cases from simple backups to complex migrations and synchronization tasks.

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