.. _Events:

Events (v0.11.0+)

The events mechanism allows lnav to be automated based on events that occur during processing. For example, filters could be added only when a particular log file format is detected instead of always installing them. Events are published through the :ref:lnav_events<table_lnav_events> SQLite table. Reacting to events can be done by creating a SQLite trigger on the table and inspecting the content of the event.

Trigger Example

The following is an example of a trigger that adds an out filter when a syslog file is loaded. You can copy the code into an :file:.sql file and install it by running :code:lnav -i my_trigger.sql.

.. code-block:: sql :caption: my_trigger.sql :linenos:

CREATE TRIGGER IF NOT EXISTS lnav_db.add_format_specific_filters
  AFTER INSERT ON lnav_db.lnav_events WHEN
    -- Check the event type
    jget(NEW.content, '/$schema') =
      'https://lnav.org/event-file-format-detected-v1.schema.json' AND
    -- Only create the filter when a given format is seen
    jget(NEW.content, '/format') = 'syslog_log' AND
    -- Don't create the filter if it's already there
    NOT EXISTS (
      SELECT 1 FROM lnav_view_filters WHERE pattern = 'noisy message')
BEGIN
INSERT INTO lnav_view_filters (view_name, enabled, type, pattern) VALUES
    ('log', 1, 'OUT', 'noisy message');
END;

.. _event_reference:

Reference

The following tables describe the schema of the event JSON objects.

.. jsonschema:: ../schemas/event-file-open-v1.schema.json# :lift_description:

.. jsonschema:: ../schemas/event-file-format-detected-v1.schema.json# :lift_description:

.. jsonschema:: ../schemas/event-log-msg-detected-v1.schema.json# :lift_description:

.. jsonschema:: ../schemas/event-session-loaded-v1.schema.json# :lift_description: