So far, we saw some hooks that Drush supports before and after running a command. In order to discover them, Drush offers a debugging mode to view all the hooks that we can implement for a given command and check whether they were executed or not on runtime.

In the following example, we will define a very simple command that we will use to test the handy option --show-invoke, which prints all the function callbacks where Drush attempts to find a match. We will create this command under $HOME/.drush/testhooks.drush.inc, which makes it available for us everywhere in the command-line interface for our user:

<?php
/**
 * @file
 * Sample Drush command to test hook invocations.
 */

/**
 * Implements hook_drush_command().
 */
function testhooks_drush_command() {
  $items = array();
  $items['testhooks'] = array(
    'description' => 'Dummy command to test command invocations.',
     // No bootstrap at all.
    'bootstrap' => DRUSH_BOOTSTRAP_DRUSH,
  );
  return...