dpkg-trigger

dpkg-trigger [option...] trigger-name
dpkg-trigger [option...] --trigger-file=trigger-file
dpkg-trigger --help | --version

--by-package=<package-name>
    Associates the triggered event with a specific package. This is commonly used by maintainer scripts to declare which package is 'responsible' for triggering the event.

--no-act
    Perform a dry run; do not actually trigger anything, but show what would be done if the command were executed normally.

--admindir=<directory>
    Set the administrative directory where dpkg stores its state information. Defaults to /var/lib/dpkg.

--root=<directory>
    Operate on a different root directory. This makes dpkg-trigger behave as if directory were the system's root directory.

--trigger-file=<file>
    Instead of specifying a trigger name (which implies an 'interest' trigger), provide the full path to a specific trigger file to be activated. This is generally used for 'activate' triggers.

--activate-awfully
    Force trigger activation, even if dependencies or other conditions are not met. Use with extreme caution as this can lead to system inconsistencies.

--verbose
    Enable verbose output, showing more details about the operations being performed.

-?, --help
    Display a short help message and exit.

--version
    Display the dpkg-trigger version information and exit.

dpkg-trigger is a utility within the dpkg package management system, designed to allow programs to manually activate dpkg triggers. dpkg triggers are a mechanism used by packages to declare that certain actions (e.g., updating font caches, rebuilding initramfs images, generating menu files) should be performed after specific events, often involving other packages or system state changes.

While dpkg automatically handles these triggers during package installation, removal, or configuration, dpkg-trigger provides a direct interface to signal such events. This is particularly useful for package maintainer scripts that might perform operations affecting other packages or requiring a trigger to run outside the standard dpkg transaction flow. By allowing explicit triggering of events, dpkg-trigger helps ensure system consistency and correct post-installation behavior, even when manual interventions or complex interactions between packages occur.

Requires sufficient privileges (typically root) to modify dpkg's administrative files.

Misuse can lead to an inconsistent package database or unexpected system behavior, especially when using --activate-awfully.

Primarily intended for use by package maintainer scripts or system administrators debugging package-related issues, not for routine end-user interaction.

dpkg triggers operate on two main types: interest and activate. Interest triggers are declared by packages that are 'interested' in a specific event or file change (e.g., interest-noawait fontconfig). When such an event occurs (often signaled by another package's maintainer script using dpkg-trigger), dpkg notes this interest. Later, when dpkg processes triggers, it runs those that have been marked as 'interested'. Activate triggers are direct calls to run a specific trigger file, often used for critical system-wide operations that need immediate attention or specific handling.

dpkg-trigger exits with 0 on success. Any other exit code indicates an error, such as invalid arguments, insufficient permissions, or internal processing failures.

The concept of triggers was introduced to dpkg to provide a more robust and flexible mechanism for post-installation/removal actions compared to simple maintainer script dependencies. dpkg-trigger emerged as a dedicated tool to allow precise and programmatic interaction with this trigger system, enabling maintainer scripts to signal events that might require other packages' triggers to run. Its development paralleled the refinement of the dpkg trigger mechanism itself, making it an integral part of complex package interactions in Debian-based systems.

dpkg(1), deb-triggers(5), maintainer-scripts(8), dpkg-reconfigure(8)