ucf

ucf [options] file

-h, --help
    Display help message and exit.

-v, --verbose
    Enable verbose output.

-d, --debug
    Enable debugging mode.

-p priority
    Set the priority of the ucf prompt (default: medium). Note: Only use during package building.

-t tmpdir
    Set the directory that will be used for temporary files (default: /tmp).

The `ucf` command is a Debian-specific utility designed to manage user modifications to configuration files during package upgrades. It compares the current configuration file with the version provided by the package upgrade and allows the user to choose how to handle the changes. This process helps prevent inadvertently overwriting user-customized configurations during system updates.

Specifically, `ucf` analyzes the differences between the old and new versions of the configuration file, and if changes are detected, prompts the user to decide whether to keep the old version, install the new version, or merge the changes. It provides options for manual intervention, enabling users to carefully integrate their custom settings with the updated defaults. This is especially useful for system administrators who need to maintain consistency across multiple servers while allowing for individual system customizations.

The `ucf` command is specific to Debian-based systems and might not be available on other Linux distributions. It primarily works within the context of package management and upgrades. Be very careful about overwriting config files.

The typical workflow involves `ucf` being called automatically by package maintainer scripts during an upgrade. The user is then prompted (if changes exist) to choose whether to keep their existing config file, install the new version, or examine the differences and manually merge changes. The goal is to automate as much as possible, while providing the user full control when needed.

For package maintainers, `ucf` can be integrated into the package building process. Using `ucf` in maintainer scripts ensures that users receive appropriate prompts and guidance when upgrading to newer versions of the package. The `-p` parameter is designed for use during package building.

The `ucf` command was developed as part of the Debian package management system to address the challenge of managing configuration file changes during package upgrades. It allows users to retain local customizations, while still incorporating updates from the package maintainers. The tool evolved as a necessity for Debian-based distributions to ensure smoother upgrade processes by preventing unintentional loss of user-specific configurations.

Early implementations lacked user-friendly prompts, but as Debian matured, so did `ucf`. The command has undergone several iterations, with improvements focusing on the clarity of the prompts and the robustness of the file comparison algorithms.

dpkg(1), apt(8), ucfr(8)