To hook my plugin content into anywhere, suppose I offered the theme developers to create their own hooks with a prefix (pre_) anywhere in their theme - the rest of the hook is unknown to me. So what will they do?

Suppose, in single.php they placed a hook like:

do_action( 'pre_kauwa' );

in page.php they placed a hook like:

do_action( 'pre_kala' );

And so on...

How can I get all those do_action() declarations with a prefix pre_ from an active WordPress installation (active theme)
from an active WordPress viewport (post, page, archive bla bla)

...so that I can make a list of hooks dynamically where my content can be hooked using add_action()?

Testing testing...

In wp-includes/plugin.php I found the has_filter() function declaration. From there I took the following line for testing:

$wp_filter = $GLOBALS['wp_filter'];
$has = ! empty( $wp_filter[ $tag ] );

In my dummy theme's index.php after the_content() (within the loop) I placed:

do_action( 'pre_kk' );

Just after the do_action() call I placed:

$t_test = $GLOBALS['wp_filter'];
$hk = 'pre_kk';
var_dump( $t_test[$hk] );

But it's throwing an undefined index.

  • 1
    Do you do add_action( 'pre_kk', 'your_function' ) to your do_action( 'pre_kk' )? Because otherwise - if I'm not totally mistaken - it won't be added to $wp_filter. Commented Apr 18, 2015 at 12:09
  • @ialocin you are right. +1 for that. But actually that couldn't solve my problem. It's returning the callback function, not the hook. :( Commented Apr 18, 2015 at 13:49
  • Because you're already addressing the specific element in the array. The first level are the hook names/tags. To get all your »pre_*« hooks you have to iterate and/or search through the array, there are plenty of threads how to do this on Stack Overflow. Or at least I don't know of a build-in functionality to do it with. Commented Apr 18, 2015 at 14:00
  • The first level are the hook names/tags. - though I'm not sure till now. I'll let you know the update. Commented Apr 18, 2015 at 16:12
  • The plugin Debug Objects give you all fired hooks in current page, also in front end. Maybe this helps you.
    – bueltge
    Commented Apr 19, 2015 at 20:24

1 Answer 1


pre_ is a terrible prefix for this because it's going to interfere with all of the WordPress internal hooks that are prefixed with pre_.

But if you want to get the name of all the actions and filters called on a certain page you can use the all hook which adds your callback to every hook. Obviously this is terribly expensive so you wouldn't want to do it on a production server.

add_action( 'all', 'wpse_all_actions' );
function wpse_all_actions() {
  static $pre = [];
  $filter = current_filter();
  if( 'pre_' === substr( $filter, 0, 4 ) ) {
    $pre[] = $filter;
  if( 'shutdown' === $filter ) {
    var_dump( $pre );

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