<?php
$info = new SplFileInfo('example.jpg');
echo info->getFilename() . ' belongs to group id ' . $info->getGroup() . "\n";
print_r(posix_getgrgid($info->getGroup()));
?>
example.jpg belongs to group id 42
Array
(
[name] => toons
[passwd] => x
[members] => Array
(
[0] => tom
[1] => jerry
)
[gid] => 42
)