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How to use mod_rewrite_rules filter in WordPress

Sandeep Kumar Mishra
Sandeep Kumar Mishra
July 12, 2022
5 minutes read

mod_rewrite_rules filter

Filters the list of rewrite rules formatted for output to an .htaccess file.

To use mod_rewrite_rules filter, first you have to register it using add_filter. You can write this code into functions.php of your activated theme or in a custom WordPress Plugin.

We at Flipper Code, always prefer to create a custom WordPress Plugin while using hooks so nothing breaks when you update your WordPress Theme in the future.

In the below live example, we have defined a function modify_mod_rewrite_rules_defaults which takes 1 parameters and we registered using add_filter. The first parameter mod_rewrite_rules is name of the hook, The second parameter modify_mod_rewrite_rules_defaults is name of the function which need to be called, third parameter is the priority of calling the hook if same hook is used multiple times and the last parameter is the number of arguments (if any) to be passed in the registered function.

Sometime, you have to remove a registered hook so you can use remove_filter to remove mod_rewrite_rules filter.


    Below the 1 parameter is required to use this hook.

  • $rules : (string) mod_rewrite Rewrite rules formatted for .htaccess.

Live Example

// Setting the X-Content-Type-Options Header
function add_headers_htaccess( $rules ) {
  $new_rule = <<<EOD
  <IfModule mod_headers.c>
  Header always set X-Content-Type-Options "nosniff"
   return $new_rule . $rules;
add_filter('mod_rewrite_rules', 'add_headers_htaccess');

Below is an example how you can use this hook.

                        function modify_mod_rewrite_rules_defaults($rules) { 
                            // Update the $rules variable according to your website requirements and return this variable. You can modify the $rules variable conditionally too if you want.

                            return $rules; 
                        // add the filter
                        add_filter( "mod_rewrite_rules", "modify_mod_rewrite_rules_defaults", 10, 1 );

To remove a hook callback, use the example below.

remove_filter( "mod_rewrite_rules", "modify_mod_rewrite_rules_defaults", 10, 1 );

Please make sure provide the same callback function name, priority and number of arguments while removing the hook callback.

Flipper Code is a Premium WordPress Plugins development company and integrating new functionalites into WordPress sites in form of custom WordPress Plugins since 2012. If you’re having any trouble using this hook, please contact our WordPress Development Team and we’d be happy to assist you.

Sandeep Kumar Mishra

Sandeep Kumar Mishra writes about WordPress and Artificial Intelligence, offering tips and guides to help you master your website and stay updated with the latest tech trends.

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