hosts-parser.php

<?php

$content = file_get_contents('/etc/hosts');
foreach (array_filter(explode("\n", $content)) as $line) {
    $parts = preg_split('/\s+/', $line);
    if (count($parts) < 2 or !preg_match('/^(?:[0-9]{1,3}\.){3}[0-9]{1,3}$/', $parts[0])) {
        continue;
    }

    list($ip, $hostName) = $parts;
}