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// -------------------------------------
//  WP version updates
// -------------------------------------

function hide_update_notice_to_all_but_admin_users()
{
    if (!current_user_can('update_core')) {
        remove_action( 'admin_notices', 'update_nag', 3 );
    }
}
add_action( 'admin_head', 'hide_update_notice_to_all_but_admin_users', 1 );

// -------------------------------------
//  WP Version updates - more robust
// -------------------------------------

add_action('after_setup_theme','remove_core_updates');
function remove_core_updates()
{
 if(! current_user_can('update_core')){return;}
 add_action('init', create_function('$a',"remove_action( 'init', 'wp_version_check' );"),2);
 add_filter('pre_option_update_core','__return_null');
 add_filter('pre_site_transient_update_core','__return_null');
}

// source: http://www.wpoptimus.com/626/7-ways-disable-update-wordpress-notifications/

// -------------------------------------
//  Plugin updates
// -------------------------------------

remove_action('load-update-core.php','wp_update_plugins');
add_filter('pre_site_transient_update_plugins','__return_null');

// source: http://www.wpoptimus.com/626/7-ways-disable-update-wordpress-notifications/


// -------------------------------------
//  All updates
// -------------------------------------

function remove_core_updates(){
global $wp_version;return(object) array('last_checked'=> time(),'version_checked'=> $wp_version,);
}
add_filter('pre_site_transient_update_core','remove_core_updates');
add_filter('pre_site_transient_update_plugins','remove_core_updates');
add_filter('pre_site_transient_update_themes','remove_core_updates');

// source: http://www.wpoptimus.com/626/7-ways-disable-update-wordpress-notifications/