Launching python script and get the result in stout in php

I have a python script abc.py that prints out "开发者_运维百科ABC". When I tried to launch this script to get the printed result in php with this code

<?php
    $cmd = "/usr/bin/python abc.py";
    $handle = popen($cmd, 'r');
    $res = fread($handle, 8192);
    pclose($handle);

    # Now you can make pretty printer about it.
    return $res;
?>

The $res is empty. And with $cmd = "/usr/bin/python abc.py 2>&1";, I got this error message /usr/bin/python: can't open file 'abc.py': [Errno 13] Permission denied.

What's wrong with this? I got same error even when I make the file abc.py accessible to everyone.

I used absolute path for python script, and changed the permission flags so that others can access, but nothing worked. I just copied the python scripts where the php scrips are located, and it works fine. I don't think this is the best way, though.