What is the best way to reset the cache of site users?

Question

PHP

Suppose all users have a cached site (js / css / img)
You have cooked a delicious borscht, to eat which you need to clear the cache.

I do like this:

#code (PHP)

$cache_url = '?08062021'; 
echo '<img src="img.png'.$cache_url.'">';

If you need to update the cache, just change the value of the variable.
There are other options? Are there better options? Is this acceptable at all?

Answer 1

Alternatively, you can use the filemtime function

echo '<img src="img.png?'.filemtime('img.png').'">';

Answer 2

$cache_url = '?' . time(); 
echo '<img src="img.png' . $cache_url.'">';

In general, in order not to be cached, then at the beginning of the script:

<?php
ob_clean();
ob_start();
header("Cache-Control: no-store, no-cache, must-revalidate, max-age=0");
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache");
?>