PHP exec / shell_exec / system does not work through browser

I am running a Unix SCO block with apache version 1.3.33 and PHP version 4.4. I can correctly execute the exec command through cli, but ran into difficulties when trying to execute the script through the browser. My settings:

• safe mode is off
• full read / write / execute permissions
• display all errors
• no disabled features

My code: test_script.php in htdocs dir

<?php
exec('ls',$out,$rval);
echo "Output:<hr />";
print "<pre>"; print_r($out); print "</pre>";
echo "Return Value:<hr />";
echo $rval;
?>

I also tried installing an executable binary path. The script test is the same user / group as apache. I also tried adding 2> & 1 to arg, but don't see the changes. Thank you in advance.

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