Passing multiple PHP variables to shell_exec()?

Variables won't interpolate inside of a single quoted string. Also you should make sure the your arguments are properly escaped.

 $page = shell_exec('/tmp/myscript.php '.escapeshellarg($my_url).' '.escapeshellarg($my_refer));

There is need to send the arguments with quota so you should use it like:

$page = shell_exec("/tmp/my_script.php '".$my_url."' '".$my_refer."'");

Change

$page = shell_exec('/tmp/my_script.php $my_url $my_refer');

to

$page = shell_exec("/tmp/my_script.php $my_url $my_refer");

OR

$page = shell_exec('/tmp/my_script.php "'.$my_url.'" "'.$my_refer.'"');

Also make sure to use escapeshellarg on both your values.

Example:

$my_url=escapeshellarg($my_url);
$my_refer=escapeshellarg($my_refer);