A simple script to recursively delete all files and directories within a parent directory

empty-directory-contents.php

<?php

/**
 * @param string $directory
 */
function emptyDirectoryContents($directory)
{
    $Iterator = new RecursiveIteratorIterator(
        new \RecursiveDirectoryIterator(
            realpath($directory),
            FilesystemIterator::SKIP_DOTS
        ), RecursiveIteratorIterator::CHILD_FIRST
    );

    /** @var \SplFileInfo $file */
    foreach ($Iterator as $file) {
        if ($file->isDir()) {
            rmdir($file->getRealPath());
        } else {
            unlink($file->getRealPath());
        }
    }
}

thanks @SenseException. It's an evolving work in progress. Should be finished a first version by the end of tomorrow.