Save an option to the database containing unexpected output during plugin activation

functions.php

<?php

/**
 * Usage: "echo get_option('plugin_error');" or look for the option the DB after activation
 * 
 * @link http://thehungrycoder.com/wordpress/how-i-have-solved-the-the-plugin-generated-xxxx-characters-of-unexpected-output-during-activation-problem.html
 */

function save_error(){
    update_option( 'plugin_error', ob_get_contents()) ;
}
add_action( 'activated_plugin','save_error' );