Admin URL to my plugin's page

Question

My plugin is basically a link display page, for instance if you want to display a page with links to other websites.

In wp-admin I have a menu item on the left side

Answer 1

You get the concrete URL to admin.php by using the admin_url function:

admin_url('admin.php'); # http(s)://localhost/wp-admin/admin.php

That function chooses the proper sheme (http/https) based on your Wordpress configuration for you so you do not need to care about it. Same for the path to the admin. The only thing you need to specify is the file name (admin.php).

And in your concrete example you add the page query-info part:

$url = admin_url('admin.php?page=customlinks');
wp_redirect($url);