$re = '/\/command\s?\S(\.\S+)?/';
$str = '/command 1
/command 0.5
/command 0.123456789
/command a
/command a.bcded
';
preg_match_all($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