Is it possible to track down Actions and Filters?

Know which file call a filter or an action is not possible running code, you have to search and read the source code or use some documentation.

There are different plugins that help you to debug the hook being fired in a page, search codex and/or Google for them.

However, to have a quick idea, add this snippet in you functions.php

class MyTracker {

  static $hooks;

  static function track_hooks( ) {
    $filter = current_filter();
    if ( ! empty($GLOBALS['wp_filter'][$filter]) ) {
      foreach ( $GLOBALS['wp_filter'][$filter] as $priority => $tag_hooks ) {
        foreach ( $tag_hooks as $hook ) {
          if ( is_array($hook['function']) )  {
            if ( is_object($hook['function'][0]) ) {
              $func = get_class($hook['function'][0]) . '->' . $hook['function'][1];
            } elseif ( is_string($hook['function'][0]) ) {
              $func = $hook['function'][0] . '::' . $hook['function'][1];
            }
          } elseif( $hook['function'] instanceof Closure ) {
            $func="a closure";
          } elseif( is_string($hook['function']) ) {
            $func = $hook['function'];
          }
          self::$hooks[] = 'On hook <b>"' . $filter . '"</b> run <b>'. $func . '</b> at priority ' . $priority;
        }
      }
    }
  }

}

add_action( 'all', array('MyTracker', 'track_hooks') );

add_action( 'shutdown', function() {
    echo implode( '<br />', MyTracker::$hooks );
}, 9999);

now visit the target page and scroll down to the bottom…

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