<?php
$groups = posix_getgroups();
print_r($groups);
?>
The above example will output
something similar to:
Array
(
[0] => 4
[1] => 20
[2] => 24
[3] => 25
[4] => 29
[5] => 30
[6] => 33
[7] => 44
[8] => 46
[9] => 104
[10] => 109
[11] => 110
[12] => 1000
)