Show the php process owner and the permissions for the current directory. Then try to write a file with file_put_contents.

file_put_contents_test.php

<?php
$processUser = posix_getpwuid(posix_geteuid());
print 'Process owner: ' . '<b style="color:blue">' . $processUser['name'] . '</b>';
echo "<br /> This directory's permisions: <i>" . exec('ls -ld') . '</i><br />';
echo file_put_contents('test.txt', 'hey there') . ' bytes written.';
?>