Include php file in Wordpress' functions.php not working for header.php

Question

I have included the line below in my functions.php file (at the top, also tried that line at the bottom of the code). I can access variables and all other stuff defined in that file in all templates . But when I try to echo $something from that file within the header.php , nothing shows up. No content, no error message.

require_once '/path/to/file.php';

Ok, after lots of trying I just found out that using the line from above inside the functions.php with

global $something;  
echo $somtehing;

in the header.php shows the value inside the wordpress header. global $something is not needed in template files though. Can please anyone explain me why?

https://secure.php.net/manual/en/reserved.variables.globals.php

Thanks!

Answer 1

I think you can create a shortcode and echo shortcode to header.php https://codex.wordpress.org/Shortcode_API

example

function foobar_func( $atts ){
    return "foo and bar";
}
add_shortcode( 'foobar', 'foobar_func' );

and call in header

<?php echo do_shortcode('[foobar]'); ?>