wp_upgrade example

delete_site_transient( 'update_core' );

if ( isset( $_GET['step'] ) ) {
    $step = $_GET['step'];
} else {
    $step = 0;
}

// Do it. No output. if ( 'upgrade_db' === $step ) {
    wp_upgrade();
    die( '0' );
}

/** * @global string $wp_version The WordPress version string. * @global string $required_php_version The required PHP version string. * @global string $required_mysql_version The required MySQL version string. * @global wpdb $wpdb WordPress database abstraction object. */
global $wp_version, $required_php_version, $required_mysql_version, $wpdb;