Warning: set_time_limit() [function.set-time-limit]: Cannot set time limit in safe mode in /home7/host7/multi/html/install/install_db.php on line 2

Warning: Cannot modify header information - headers already sent by (output started at /home7/host7/multi/html/install/install_db.php:2) in /home7/host7/multi/html/install/install_db.php on line 19

Warning: Cannot modify header information - headers already sent by (output started at /home7/host7/multi/html/install/install_db.php:2) in /home7/host7/multi/html/install/install_db.php on line 20

Warning: Cannot modify header information - headers already sent by (output started at /home7/host7/multi/html/install/install_db.php:2) in /home7/host7/multi/html/install/install_db.php on line 21

Warning: Cannot modify header information - headers already sent by (output started at /home7/host7/multi/html/install/install_db.php:2) in /home7/host7/multi/html/install/install_db.php on line 22

Warning: Cannot modify header information - headers already sent by (output started at /home7/host7/multi/html/install/install_db.php:2) in /home7/host7/multi/html/install/install_db.php on line 23

라고 뜨는군요, 설치중 처음 발생한 에러인데 이상이 없는 부분인지 알고싶습니다.

요즘 그누공부를 통 못해서... 아시는분들 답변 달아주시길 바랍니다.

ps. 다음은 install_db.php의 내용중 문제가되는 2~23라인까지의 내용입니다.
set_time_limit(0);

include_once ("../config.php");

// 파일이 존재한다면 설치할 수 없다.
if (file_exists("../dbconfig.php")) {
    echo "<meta http-equiv='content-type' content='text/html; charset=$g4[charset]'>";
    echo <<<HEREDOC
    <script language="JavaScript">
    alert("설치하실 수 없습니다.");
    location.href="../";
    </script>
HEREDOC;
    exit;
}

$gmnow = gmdate("D, d M Y H:i:s") . " GMT";
header("Expires: 0"); // rfc2616 - Section 14.21
header("Last-Modified: " . $gmnow);
header("Cache-Control: no-store, no-cache, must-revalidate"); // HTTP/1.1
header("Cache-Control: pre-check=0, post-check=0, max-age=0"); // HTTP/1.1
header("Pragma: no-cache"); // HTTP/1.0

설치는 되고 별다른 이상을 발견하지는 못했습니다만, 왠지 궁금해서요..ㅎ