inserts content after opening body tag

POST Body tag insert

add_filter('template_include','yoursite_template_include',1);
function yoursite_template_include($template) {
	ob_start();
	return $template;
}
add_filter('shutdown','yoursite_shutdown',0);
function yoursite_shutdown() {
	$insert =  "\n<!--YOUR INSERTED ". get_option('setting_a') ." HTML GOES HERE-->";
	$content = ob_get_clean();
	$content = preg_replace('#<body([^>]*)>#i',"<body$1>{$insert}",$content);
	echo $content;
}