$re = '/(<title><\?php echo L10n::message\(\'label.edit\')(.*?)(<\/title>)/m';
$str = '<title><?php echo L10n::message(\'label.edit\', L10n::label(\'location\')); ?></title>
<title><?php echo L10n::message(\'label.edit\', L10n::label(\'manufacturer\', rrue)); ?></title>
<title><?php echo L10n::message(\'label.edit\', L10n::label(\'items.de\')); ?></title>
<title><?php echo L10n::message(\'label.edit\', L10n::label(\'water_as\')); ?></title>';
$subst = "<title><?php echo L10n::label('edit'); ?></title>";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
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