Cheatset for multinetwork

wp-multinetwork.php

<?php 

/**
 * Grant newly superadmin user to all networks when working in a multi-network context
 * @author Maxime CULEA
 */
add_action( 'grant_super_admin', 'superadmin_is_superadmin_for_all_networks' );
function superadmin_is_superadmin_for_all_networks( $user_id ) {
	remove_action( 'grant_super_admin', 'superadmin_is_superadmin_for_all_networks' );
	global $wpdb;

	$results = $wpdb->get_col( "SELECT id FROM {$wpdb->site}" );

	if ( ! empty( $results ) ) {
		$current_network = get_current_network_id();
		foreach ( $results as $network_id ) {
			switch_to_network( (int) $network_id );
			grant_super_admin( $user_id );
		}
		switch_to_network( $current_network );
	}
}