MaybeJustMaybe

Instead of having a plugin, I’d like to learn how to add this myself. I want to PROGRAM it but not use it as plugin.

I wrote this part after reading, here comes to next part after I tried enabling it (it is included in the link you provided):

So my code is not changed a lot, it’s this:

<?php

// Plugin Name: Experiment

	add_filter( 'pre_option_link_manager_enabled', '__return_true' );

    $linkdata = array(
	'link_name' => 'I"M HERE!!',
	'link_url' => 'http://codex.wordpress.org'
    );

    wp_insert_link( $linkdata, true);

?>

I went to 127.0.0.1/prj/wp-admin/options.php. And changed link_manager_enabled. From 0 to 1. And there’s still no link.