How to get URL string into PHP variable

Let's start with an example:

So requested URL would be: www.domain.com/product/hdd/samsung

I want to have a rewrite rule to get index.php and save everything after www.domain.com into php varible. So, substituted page would be for example www.domain.com/index.php?query=product/hdd/samsung. But I'am unable to write correct rule.

I tried this:

RewriteRule ^/(.*)$ index.php?query=$1 [NC,L]
 

The code above isn't working. I want to use the query in PHP code in the index.php:

if(isset($_GET["query"] )) {
    $query=$_GET["query"];
 }
 

I find out, there is possibility to get $query via $_SERVER['QUERY_STRING'], am I right?

For my PHP application is varibale $query critical, because it's used for loading templates.

Questions:
What solution would you recomand me? To use $_SERVER variable or mod_rewrite?
If mod_rewrite, how to write correct RewriteRule?

Thank you

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