PHP. Использование итераторов директорий.

$directory = new \RecursiveDirectoryIterator('./datafiles');
$iterator = new \RecursiveIteratorIterator($directory);
$regex = new \RegexIterator($iterator, '/\w+\.ixt/i',
                \RecursiveRegexIterator::GET_MATCH);
$files = array();
foreach($regex as $file) {
    $files[] = $file[0];
}
sort($files);
print_r($files);

Array
(
    [0] => akjkdsjff3.ixt
    [1] => dfsd8878.ixt
    [2] => skka878.ixt
    [3] => zwsdf8sdk.ixt
)