Shortcodes

https://codex.wordpress.org/Shortcode

[my_shortcode id=1]

function my_shortcode_shortcode( $atts, $content = null ) {

	ob_start();
	?> <h1>Title</h1>
	<?php dump($atts); ?>
	<?php 
	return ob_get_clean();

}

add_shortcode("my_shortcode", "my_shortcode_shortcode");

Shortcode redirect

functions.php

function ob_start_global (){
	ob_start ();
}
add_action ('init', 'ob_start_global');

function ob_flush_global (){
	echo ob_get_clean ();
}
add_action ('shutdown', 'ob_flush_global');