<?php
$files = [];
$dir = new RecursiveDirectoryIterator('/home/digvputi/growthradar/');
$iter = new RecursiveIteratorIterator($dir);
foreach ($iter as $file) {
    if ($file->getExtension() === 'php') {
        $files[] = $file->getPathname();
    }
}
sort($files);
echo '<pre>' . implode("\n", $files) . '</pre>';