<IfModule mod_rewrite.c>
 RewriteEngine On
 RewriteBase /cms_project
 RewriteCond %{REQUEST_URI} single(.*)
 RewriteRule  ^(.+)$ single.php?url=$1
</IfModule>

//want to query strings single/posts/1/post-title
echo $_GET['url'];

OR

//function to get url query string convert it to an array
function getUrl() {
    if(isset($_GET['url'])) {
        $url = rtrim($_GET['url'],'/');
        $url = filter_var($url, FILTER_SANITIZE_URL);
        $url = explode('/', $url);
        return $url;
    }
  }
  print_r($_GET['url']);