Различные вопросы по PHP и MySQL

<?
$msg= str_replace('
',<br />,$msg); // вырезаем новую строку
?>

<?php
$s = "new\n\line\r\nanother line";
echo $s;
echo "\n------------------\n";
$s = preg_replace('~\s~', '', $s);
echo $s;

[~] >>> cat t.php
<?php
$s = "new\n\line\r\nanother line";
echo $s;
echo "\n------------------\n";
$s = preg_replace('~[\r\n]~', '', $s);
echo $s;
[~] >>> php t.php
new
\line
another line
------------------
new\lineanother line

$s = preg_replace('~\s~', '<br />', $s);