check url parameter if not redirect wordpress plugin

To check a URL parameter and redirect in a WordPress plugin, follow these steps:

1. Create a WordPress Plugin: Create a new folder in the wp-content/plugins/ directory of your WordPress installation. Inside this folder, create a PHP file for your plugin.

2. Define Plugin Header: Add the plugin header to the PHP file to provide information about the plugin. This includes details like the plugin name, description, version, and author.

php /* Plugin Name: Custom Redirect Plugin Description: Redirects based on URL parameters. Version: 1.0 Author: Your Name */

1. Implement the Redirection Logic: Add code to check the URL parameter and perform the redirection if necessary. Use the WordPress init action hook to execute this code during the initialization process.

```php function custom_redirect() { // Check if the 'redirect_param' parameter is present in the URL if (isset($_GET['redirect_param'])) { // Get the value of the 'redirect_param' parameter $redirect_url = esc_url($_GET['redirect_param']);

       // Perform the redirection
       wp_redirect($redirect_url);
       exit;
   }

}

add_action('init', 'custom_redirect'); ```

This code checks if the 'redirect_param' parameter is present in the URL. If found, it retrieves the parameter value, sanitizes it, and redirects the user to the specified URL.

1. Activate the Plugin: Log in to your WordPress admin dashboard, navigate to the "Plugins" section, and activate your custom plugin.

2. Testing: Append the parameter to a URL to test the redirection. For example: http://yourwordpresssite.com/?redirect_param=http://destinationurl.com

Accessing the above URL should trigger the redirection based on the provided parameter.

Remember to replace 'redirect_param' with the actual parameter you want to check, and customize the redirection logic as needed for your specific use case.