如何从HTML网页在unix服务器上执行php文件

I have a webpage with a HTML button. The webpage is located in /var/www/html and is named index.php. In the same folder I have a file called "running.php". The contents of running.php is below:

#!/usr/bin/php

<?php

    if(isset($_POST['action']) && !empty($_POST['action'])) {

        $action = $_POST['action'];

        switch($action) {

            case 'test' : test();

            break;

        }
    }


    function test(){

         exec("/usr/sapint/outgoing/ihprocess",$output);

         print_r($output);

   }
?>

when I run the file from command line on the server as ./running.php the file executes perfectly. I want to be able to execute this file from the HTML webpage.

I have played around with all the options such as exec, permissions etc but nothing seems to work.

I currently have in my index.php file

<a id="run" class="btn btn-primary" onclick="ajaxcall()">Process Files </a>

   function ajaxcall() {    

    $.ajax({ url: 'running.php',
     data: {action: 'test'},
     type: 'post',
     success: function(output) {
                  alert(output);
              }
  });

}

any help would be appreciated.