$re = '/^0[123]*(?:{[^{}]*}[123]*)*0/m';
$str = '0213123123130
012312312312303123123
01231230123123031230
01232231{whatever 3 gArBaGe? I want.}121{foo}2310312{bar}3120123
01212121{hello 0}121312
01213123123123{21310030123012301}31231230123';
preg_match_all($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