Check which user is running under web server

check-user-web.php

<?
echo "I am running as user=";
system("whoami");
echo "<P>I can write here= ";
system("pwd");
$fname="write_test.txt";
if (file_exists($fname)) {
        echo "<P> I found file $fname and will delete it";
        unlink($fname);
        echo "...Done";
        }
echo "<P>I'm writing new file $fname";
system ("touch $fname");
?>