Assume that some other plugin or theme uses a add_action hook. Is there a way to determine if a specific hook is being used by someone else?

Example: assume that a plugin has this code

add_action ( 'publish_post', 'myCustomFunction' );
function myCustomFunction() {
   // does something

Can my plugin 'look' for the use of that hook into 'publish_post'? And can I remove that particular action hook before it fires?


You can use has_action(). It returns the priority of the hook if it exists, otherwise false. So check that the priority is not equal to false (and not just false-y, or being hooked at 0 will appear false) then use that to remove the hook.

$priority = has_action( 'publish_post', 'myCustomFunction' );

if ( $priority !== false ) {
    remove_action( 'publish_post', 'myCustomFunction', $priority );

There's also has_filter(), which does exactly the same thing (has_action() just calls has_filter()).

| improve this answer | |
  • Sudden thought: is there then a way to tell where that action was defined (the source file that contains that do_action)? – Rick Hellewell May 24 '18 at 3:16
  • I don't believe so. When adding hooks it's possible that the file with the do_action() hasn't even been loaded yet. – Jacob Peattie May 24 '18 at 5:07
  • Looking for the file that contained the do_action, not the file that will process it. So if my_plugin.php contains a 'do_action', is there any way to log/determine that my_plugin.php was the 'culprit'? – Rick Hellewell May 25 '18 at 1:41
  • Do you mean add_action()? – Jacob Peattie May 25 '18 at 1:43
  • Whoops. Yes. Would be interesting to know what file has the add_action function, without having to scan all files. – Rick Hellewell May 25 '18 at 17:28

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