<?php
echo 'php_ver: ' . phpversion() . "\n";

$pattern = '/^\^\s([a-z])\1+$/m';
$subject = "^ aaa\n^ bbb\n^ ccc";

preg_match_all($pattern, $subject, $m, PREG_SET_ORDER);

foreach ($m as $v) {
    echo "{$v[0]}\n";
}
?>