$re = '/([a-zA-Z-]*[a-zA-Z]+\.){1,}[a-zA-Z-]*[a-zA-Z]+$/m';
$str = 'abc123
1edc2
-blub
notthisone-
ornament
---a
abc123.def
---a.-----b
not.-this-
-inc-clude-a.this
-ex-clude-.this
github-bg.com.uk.bg
';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php