header

(PHP 4, PHP 5, PHP 7, PHP 8)

header — Ham bir HTTP başlığı gönderir

Açıklama

header(string $başlık, bool $değiştir = true, int $http_yanıt_kodu = 0): void

header() işlevi ham bir HTTP başlığı göndermek için kulanılır. HTTP başlıkları hakkında ayrıntılı bilgi edinmek için » HTTP/1.1 Belirtimi'ne bakınız.

header() işlevinin normal HTML etiketleri ve dosya veya PHP'deki boş satırlar dahil herhangi bir çıktıdan önce çağrılması gerektiğini unutmayınız. header() çağrısından önce sıkça yapılan hatalar: kodu include, require veya başka bir dosya okuma işlevi ile okumak; betik HTML'ye gömülüyse betiğin veya dosyanın başındaki boşluklar veya boş satırlar.

<html>
<?php
/* Bu bir hata verecektir.  header() çağrısından
 * önce hiçbir satırlar olmamalıydı. */
header('Location: http://localhost/');
exit;
?>

Bağımsız Değişkenler

başlık

Başlık dizgesi.

İki özel çağrı biçimi vardır. İlki, HTTP durum kodu gönderilirken kullanılır ve başlık "HTTP/" dizgesi ile başlar (harf büyüklüğüne duyarsız). Örneğin Apache'yi eksik dosyalarla ilgili sorunlar için (ErrorDocument yönergesi ile) bir PHP betiğini kullanacak şekilde yapılandırmışsanız betiğinizde uygun bir durum kodu üretmek için bu biçimi kullanabilirsiniz.

<?php
// Bu örnekte "HTTP/" için özel bir durum gösterilmiştir.
// Her durumda geçerli olacak kullanım şöyle olurdu:
// 1. header($_SERVER["SERVER_PROTOCOL"] . " 404 Not Found");
//    (Hala HTTP/1.0 kullanan istemci için http durum iletisinin yerini alır)
// 2. http_response_code(404); (öntanımlı iletiyi kullanmak için)
header("HTTP/1.1 404 Not Found");
?>

İkinci özel biçim "Location:" başlığıdır. Bu başlığın tarayıcıya geri gönderilmesinden başka, bir 201 veya 3xx durum kodu henüz atanmamışsa ayrıca bir REDIRECT (302) durum kodu da gönderilir.

<?php
header("Location: http://mesela.dom/"); /* Tarayıcıyı yönlendir */

/* Yönlendirme sonrası herhangi bir kodun çalıştırılmamasını sağlayalım. */
exit;
?>

değiştir

değiştir bağımsız değişkeni isteğe bağlı olup, önceki bir başlığın mı değiştireceğini yoksa aynı türde ikinci bir başlık daha mı ekleneceğini belirtilir. Öntanımlı davranış mevcudu değiştirmektir. İşleve ikinci bağımsız değişken olarak false aktarırsanız aynı türde çok sayıda başlık bulunması için işlevi zorlamış olursunuz. Örnek:

<?php
header('WWW-Authenticate: Negotiate');
header('WWW-Authenticate: NTLM', false);
?>

http_yanıt_kodu

HTTP yanıt kodunu belirtilen değere zorlar. Bu bağımsız değişken sadece başlık bağımsız değişkeni boş değilse etkilidir.

Dönen Değerler

Hiçbir değer dönmez.

Hatalar/İstisnalar

Gönderilecek başlığın zamanlamasındaki bir başarısızlık, header() işlevinin E_WARNING seviyesinde bir hata çıktılamasına sebep olur.

Örnekler

Örnek 1 - İndirme söyleşisi

Kulanıcıyı, gönderdiğiniz veriyi (örneğin, bir PDF dosyası) kaydetmesi için uyarmak isterseniz, bir dosya ismi belirtmek ve tarayıcının bir dosya kayıt söyleşisi göstermesini sağlamak için » Content-Disposition başlığını kullanabilirsiniz.

<?php
// Bir PDF çıktılayacağız
header('Content-Type: application/pdf');

// Dosya ismi indirilen.pdf olsun
header('Content-Disposition: attachment; filename="indirilen.pdf"');

// Okunacak PDF dosyası
readfile('original.pdf');
?>

Örnek 2 - Yönergelerin önbelleklenmesi

PHP betikleri çoğunlukla istemcinin tarayıcısı veya sunucuya aracılık eden vekiller tarafından önbelleğe alınmaması gereken dinamik içerikler üretirler. Çoğu vekilin veya tarayıcının önbellekleme işlemini kapatmasını şöyle sağlayabilirsiniz:

<?php
header("Cache-Control: no-cache, must-revalidate"); // HTTP/1.1
header("Expires: Sat, 26 Jul 1997 05:00:00 GMT"); // Geçmişte bir tarih
?>

Bilginize:
Yukarıdaki başlıkların hiçbirini çıktılamadığınız halde sayfalarınız önbelleğe alınmıyor olabilir. Kullanıcının kendi tarayıcısının önbellekleme ile ilgili öntanımlı davranışını değiştirebileceği çok çeşitli seçenekleri olabilir. Yukarıdaki başlıkları göndererek bu tür olası ayarları geçersiz kılabilirsiniz.

Ayrıca, oturumları kullanırken önbellekleme ile ilgili doğru başlıkların otomatik olarak üretilmesi için session_cache_limiter() işlevini ve session.cache_limiter yapılandırma yönergesini kullanabilirsiniz.

Notlar

Bilginize:
Başlıklar sadece onları destekleyen bir SAPI kullanımdaysa erişilebilir ve çıktılanabilir olacaktır.

Bilginize:
PHP 4'ten itibaren, bu işlevi çağırmadan önce, tarayıcıya gönderilene kadar sunucuda bekletilmek üzere çıktıyı bir tampona yazabilirsiniz. Bu işlemi betiğinizden ob_start() ve ob_end_flush() işlevlerini çağırarak veya output_buffering yapılandırma yönergesini php.ini veya sunucu yapılandırma dosyalarında belirterek yapabilirsiniz.

Bilginize:
header() çağrısının ilk çağrı olup olmamasından bağımsız olarak istemciye ilk olarak daima HTTP durum başlığı satırı gönderilir. header() işlevini hiçbir HTTP başlığı gönderilmeden önce yeni bir durum satırı ile kullanırsanız bu durum satırını geçersiz kılabilirsiniz.

Bilginize:
Çoğu çağdaş istemci » Location: için bağımsız değişken olarak göreli bir URI kabul etmektedir, fakat bazı eski istemciler şema, konak ismi ve mutlak dosya yolu içeren mutlak bir URI gerektirir. Bir mutlak URI'yi bir göreli URI'ye dönüştürmek için örnekteki gibi $_SERVER['HTTP_HOST'], $_SERVER['PHP_SELF'] ve dirname() kullanabilirsiniz:

<?php /* Bulunulan dizinde başka bir sayfaya yönlendirelim */ $konak = $_SERVER['HTTP_HOST']; $yol = rtrim(dirname($_SERVER['PHP_SELF']), '/\\'); $ek = 'sayfam.php'; header("Location: http://$konak$yol/$ek"); exit; ?>

Bilginize:
Oturum kimliği, session.use_trans_sid etkin olsa bile Location başlığı ile aktarılmaz. SID sabiti kullanılarak elle aktarılmalıdır.

Ayrıca Bakınız

headers_sent() - Başlıklar gönderilmiş mi, gönderilmişse nerede gönderilmiş diye bakar
setcookie() - Bir çerez gönderir
http_response_code() - HTTP yanıt kodunu tanımlar veya siler
header_remove() - Evvelce tanımlanmış başlıkları siler
headers_list() - Gönderilmiş (veya gönderilmeye hazır) yanıt başlıklarının listesiyle döner

＋add a note

User Contributed Notes 33 notes

down

244

mjt at jpeto dot net ¶

14 years ago

I strongly recommend, that you use



header($_SERVER["SERVER_PROTOCOL"]." 404 Not Found");



instead of 



header("HTTP/1.1 404 Not Found");



I had big troubles with an Apache/2.0.59 (Unix) answering in HTTP/1.0 while I (accidentially) added a "HTTP/1.1 200 Ok" - Header.



Most of the pages were displayed correct, but on some of them apache added weird content to it:



A 4-digits HexCode on top of the page (before any output of my php script), seems to be some kind of checksum, because it changes from page to page and browser to browser. (same code for same page and browser)



"0" at the bottom of the page (after the complete output of my php script) 



It took me quite a while to find out about the wrong protocol in the HTTP-header.

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168

Marcel G ¶

14 years ago

Several times this one is asked on the net but an answer could not be found in the docs on php.net ...



If you want to redirect an user and tell him he will be redirected, e. g. "You will be redirected in about 5 secs. If not, click here." you cannot use header( 'Location: ...' ) as you can't sent any output before the headers are sent.



So, either you have to use the HTML meta refresh thingy or you use the following:



<?php

  header( "refresh:5;url=wherever.php" );

  echo 'You\'ll be redirected in about 5 secs. If not, click <a href="wherever.php">here</a>.';

?>



Hth someone

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Dylan at WeDefy dot com ¶

16 years ago

A quick way to make redirects permanent or temporary is to make use of the $http_response_code parameter in header().

<?php
// 301 Moved Permanently
header("Location: /foo.php",TRUE,301);

// 302 Found
header("Location: /foo.php",TRUE,302);
header("Location: /foo.php");

// 303 See Other
header("Location: /foo.php",TRUE,303);

// 307 Temporary Redirect
header("Location: /foo.php",TRUE,307);
?>

The HTTP status code changes the way browsers and robots handle redirects, so if you are using header(Location:) it's a good idea to set the status code at the same time.  Browsers typically re-request a 307 page every time, cache a 302 page for the session, and cache a 301 page for longer, or even indefinitely.  Search engines typically transfer "page rank" to the new location for 301 redirects, but not for 302, 303 or 307. If the status code is not specified, header('Location:') defaults to 302.

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Emmanuel Chazard ¶

9 months ago

If you use header() to allow the user to download a file, it's very important to check the encoding of the script itself. Your script should be encoded in UTF-8, but definitely not in UTF-8-BOM! The presence of BOM will alter the file received by the user. Let the following script: 

<?php 

$content = file_get_contents('test_download.png') ;
$name = 'test.png' ;
$size = strlen($content) ;
    
header('Content-Description: File Transfer');
header('Content-Type: application/octet-stream');
header('Cache-Control: no-cache, must-revalidate');
header('Expires: 0');
header('Content-Disposition: attachment; filename="'.$name.'"');
header('Content-Length: ' . $size);
header('Pragma: public');

echo $content ;

?>

Irrespectively from the encoding of test_download.png, when this PHP script is encoded in UTF-8-BOM, the content received by the user is different: 
- a ZWNBSP byte (U+FEFF) is added to the beginning of the file
- the file content is truncated!!!
If it's a binary file (e.g. image, proprietary format), the file will become unreadable.

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mandor at mandor dot net ¶

18 years ago

When using PHP to output an image, it won't be cached by the client so if you don't want them to download the image each time they reload the page, you will need to emulate part of the HTTP protocol.

Here's how:

<?php

    // Test image.
    $fn = '/test/foo.png';

    // Getting headers sent by the client.
    $headers = apache_request_headers(); 

    // Checking if the client is validating his cache and if it is current.
    if (isset($headers['If-Modified-Since']) && (strtotime($headers['If-Modified-Since']) == filemtime($fn))) {
        // Client's cache IS current, so we just respond '304 Not Modified'.
        header('Last-Modified: '.gmdate('D, d M Y H:i:s', filemtime($fn)).' GMT', true, 304);
    } else {
        // Image not cached or cache outdated, we respond '200 OK' and output the image.
        header('Last-Modified: '.gmdate('D, d M Y H:i:s', filemtime($fn)).' GMT', true, 200);
        header('Content-Length: '.filesize($fn));
        header('Content-Type: image/png');
        print file_get_contents($fn);
    }

?>

That way foo.png will be properly cached by the client and you'll save bandwith. :)

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bebertjean at yahoo dot fr ¶

15 years ago

If using the 'header' function for the downloading of files, especially if you're passing the filename as a variable, remember to surround the filename with double quotes, otherwise you'll have problems in Firefox as soon as there's a space in the filename.

So instead of typing:

<?php
  header("Content-Disposition: attachment; filename=" . basename($filename));
?>

you should type:

<?php
  header("Content-Disposition: attachment; filename=\"" . basename($filename) . "\"");
?>

If you don't do this then when the user clicks on the link for a file named "Example file with spaces.txt", then Firefox's Save As dialog box will give it the name "Example", and it will have no extension.

See the page called "Filenames_with_spaces_are_truncated_upon_download" at 
http://kb.mozillazine.org/ for more information. (Sorry, the site won't let me post such a long link...)

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php at ober-mail dot de ¶

4 years ago

Since PHP 5.4, the function `http_response_code()` can be used to set the response code instead of using the `header()` function, which requires to also set the correct protocol version (which can lead to problems, as seen in other comments).

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David Spector ¶

2 years ago

Please note that there is no error checking for the header command, either in PHP, browsers, or Web Developer Tools.

If you use something like "header('text/javascript');" to set the MIME type for PHP response text (such as for echoed or Included data), you will get an undiagnosed failure.

The proper MIME-setting function is "header('Content-type: text/javascript');".

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yjf_victor ¶

8 years ago

According to the RFC 6226 (https://tools.ietf.org/html/rfc6266), the only way to send Content-Disposition Header with encoding is:

Content-Disposition: attachment;
                          filename*= UTF-8''%e2%82%ac%20rates

for backward compatibility, what should be sent is:

Content-Disposition: attachment;
                          filename="EURO rates";
                          filename*=utf-8''%e2%82%ac%20rates

As a result, we should use

<?php
$filename = '中文文件名.exe';   // a filename in Chinese characters

$contentDispositionField = 'Content-Disposition: attachment; '
    . sprintf('filename="%s"; ', rawurlencode($filename))
    . sprintf("filename*=utf-8''%s", rawurlencode($filename));

header('Content-Type: application/octet-stream');

header($contentDispositionField);

readfile('file_to_download.exe');
?>

I have tested the code in IE6-10, firefox and Chrome.

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tim at sharpwebdevelopment dot com ¶

6 years ago

The header call can be misleading to novice php users.
when "header call" is stated, it refers the the top leftmost position of the file and not the "header()" function itself.
"<?php" opening tag must be placed before anything else, even whitespace.

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sk89q ¶

15 years ago

You can use HTTP's etags and last modified dates to ensure that you're not sending the browser data it already has cached.



<?php

$last_modified_time = filemtime($file);

$etag = md5_file($file);



header("Last-Modified: ".gmdate("D, d M Y H:i:s", $last_modified_time)." GMT");

header("Etag: $etag");



if (@strtotime($_SERVER['HTTP_IF_MODIFIED_SINCE']) == $last_modified_time ||

    trim($_SERVER['HTTP_IF_NONE_MATCH']) == $etag) {

    header("HTTP/1.1 304 Not Modified");

    exit;

}

?>

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nospam at nospam dot com ¶

8 years ago

<?php

// Response codes behaviors when using 
header('Location: /target.php', true, $code) to forward user to another page:

$code = 301;
// Use when the old page has been "permanently moved and any future requests should be sent to the target page instead. PageRank may be transferred."

$code = 302; (default)
// "Temporary redirect so page is only cached if indicated by a Cache-Control or Expires header field."

$code = 303;
// "This method exists primarily to allow the output of a POST-activated script to redirect the user agent to a selected resource. The new URI is not a substitute reference for the originally requested resource and is not cached."

$code = 307;
// Beware that when used after a form is submitted using POST, it would carry over the posted values to the next page, such if target.php contains a form processing script, it will process the submitted info again!

// In other words, use 301 if permanent, 302 if temporary, and 303 if a results page from a submitted form.
// Maybe use 307 if a form processing script has moved.

?>

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ben at indietorrent dot org ¶

11 years ago

Be aware that sending binary files to the user-agent (browser) over an encrypted connection (SSL/TLS) will fail in IE (Internet Explorer) versions 5, 6, 7, and 8 if any of the following headers is included:

Cache-control:no-store
Cache-control:no-cache

See: http://support.microsoft.com/kb/323308

Workaround: do not send those headers.

Also, be aware that IE versions 5, 6, 7, and 8 double-compress already-compressed files and do not reverse the process correctly, so ZIP files and similar are corrupted on download.

Workaround: disable compression (beyond text/html) for these particular versions of IE, e.g., using Apache's "BrowserMatch" directive. The following example disables compression in all versions of IE:

BrowserMatch ".*MSIE.*" gzip-only-text/html

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David ¶

6 years ago

It seems the note saying the URI must be absolute is obsolete. Found on https://en.wikipedia.org/wiki/HTTP_location

«An obsolete version of the HTTP 1.1 specifications (IETF RFC 2616) required a complete absolute URI for redirection.[2] The IETF HTTP working group found that the most popular web browsers tolerate the passing of a relative URL[3] and, consequently, the updated HTTP 1.1 specifications (IETF RFC 7231) relaxed the original constraint, allowing the use of relative URLs in Location headers.»

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jp at webgraphe dot com ¶

20 years ago

A call to session_write_close() before the statement



<?php

    header("Location: URL");

    exit();

?>



is recommended if you want to be sure the session is updated before proceeding to the redirection.



We encountered a situation where the script accessed by the redirection wasn't loading the session correctly because the precedent script hadn't the time to update it (we used a database handler).



JP.

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dev at omikrosys dot com ¶

14 years ago

Just to inform you all, do not get confused between Content-Transfer-Encoding and Content-Encoding

Content-Transfer-Encoding specifies the encoding used to transfer the data within the HTTP protocol, like raw binary or base64. (binary is more compact than base64. base64 having 33% overhead).
Eg Use:- header('Content-Transfer-Encoding: binary');

Content-Encoding is used to apply things like gzip compression to the content/data.
Eg Use:- header('Content-Encoding: gzip');

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shutout2730 at yahoo dot com ¶

15 years ago

It is important to note that headers are actually sent when the first byte is output to the browser. If you are replacing headers in your scripts, this means that the placement of echo/print statements and output buffers may actually impact which headers are sent. In the case of redirects, if you forget to terminate your script after sending the header, adding a buffer or sending a character may change which page your users are sent to.

This redirects to 2.html since the second header replaces the first.

<?php
header("location: 1.html"); 
header("location: 2.html"); //replaces 1.html
?>

This redirects to 1.html since the header is sent as soon as the echo happens. You also won't see any "headers already sent" errors because the browser follows the redirect before it can display the error.

<?php
header("location: 1.html");
echo "send data"; 
header("location: 2.html"); //1.html already sent 
?>

Wrapping the previous example in an output buffer actually changes the behavior of the script! This is because headers aren't sent until the output buffer is flushed.

<?php
ob_start();
header("location: 1.html"); 
echo "send data"; 
header("location: 2.html"); //replaces 1.html
ob_end_flush(); //now the headers are sent
?>

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chris at ocproducts dot com ¶

7 years ago

Note that 'session_start' may overwrite your custom cache headers.
To remedy this you need to call:

session_cache_limiter('');

...after you set your custom cache headers. It will tell the PHP session code to not do any cache header changes of its own.

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Refugnic ¶

14 years ago

My files are in a compressed state (bz2). When the user clicks the link, I want them to get the uncompressed version of the file.

After decompressing the file, I ran into the problem, that the download dialog would always pop up, even when I told the dialog to 'Always perform this operation with this file type'.

As I found out, the problem was in the header directive 'Content-Disposition', namely the 'attachment' directive.

If you want your browser to simulate a plain link to a file, either change 'attachment' to 'inline' or omit it alltogether and you'll be fine.

This took me a while to figure out and I hope it will help someone else out there, who runs into the same problem.

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-1

razvan_bc at yahoo dot com ¶

6 years ago

<?php
/* This will give an error. Note the output
 * above, which is before the header() call */
header('Location: http://www.example.com/');
exit;
?>

this example is pretty good BUT in time you use "exit" the parser will still work to decide what's happening next the "exit" 's action should do ('cause if you check the manual exit works in others situations too).
SO MY POINT IS : you should use :
<?php

header('Location: http://www.example.com/');
die();

?>
'CAUSE all die function does is to stop the script ,there is no other place for interpretation and the scope you choose to break the action of your script is quickly DONE!!!

there are many situations  with others examples and the right choose for small parts of your scrips that make differences when you write your php framework at well! 

Thanks Rasmus Lerdorf and his team to wrap off parts of unusual php functionality ,php 7 roolez!!!!!

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mzheng[no-spam-thx] at ariba dot com ¶

15 years ago

For large files (100+ MBs), I found that it is essential to flush the file content ASAP, otherwise the download dialog doesn't show until a long time or never. 

<?php
header("Content-Disposition: attachment; filename=" . urlencode($file));    
header("Content-Type: application/force-download");
header("Content-Type: application/octet-stream");
header("Content-Type: application/download");
header("Content-Description: File Transfer");             
header("Content-Length: " . filesize($file));
flush(); // this doesn't really matter.

$fp = fopen($file, "r"); 
while (!feof($fp))
{
    echo fread($fp, 65536); 
    flush(); // this is essential for large downloads
}  
fclose($fp); 
?>

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Cody G. ¶

13 years ago

After lots of research and testing, I'd like to share my findings about my problems with Internet Explorer and file downloads.

  Take a look at this code, which replicates the normal download of a Javascript:

<?php
 if(strstr($_SERVER["HTTP_USER_AGENT"],"MSIE")==false) {
  header("Content-type: text/javascript");
  header("Content-Disposition: inline; filename=\"download.js\"");
  header("Content-Length: ".filesize("my-file.js"));
 } else {
  header("Content-type: application/force-download");
  header("Content-Disposition: attachment; filename=\"download.js\"");
  header("Content-Length: ".filesize("my-file.js"));
 }
 header("Expires: Fri, 01 Jan 2010 05:00:00 GMT");
 if(strstr($_SERVER["HTTP_USER_AGENT"],"MSIE")==false) {
  header("Cache-Control: no-cache");
  header("Pragma: no-cache");
 }
 include("my-file.js");
?>

Now let me explain:

  I start out by checking for IE, then if not IE, I set Content-type (case-sensitive) to JS and set Content-Disposition (every header is case-sensitive from now on) to inline, because most browsers outside of IE like to display JS inline. (User may change settings). The Content-Length header is required by some browsers to activate download box. Then, if it is IE, the "application/force-download" Content-type is sometimes required to show the download box. Use this if you don't want your PDF to display in the browser (in IE). I use it here to make sure the box opens. Anyway, I set the Content-Disposition to attachment because I already know that the box will appear. Then I have the Content-Length again.

  Now, here's my big point. I have the Cache-Control and Pragma headers sent only if not IE. THESE HEADERS WILL PREVENT DOWNLOAD ON IE!!! Only use the Expires header, after all, it will require the file to be downloaded again the next time. This is not a bug! IE stores downloads in the Temporary Internet Files folder until the download is complete. I know this because once I downloaded a huge file to My Documents, but the Download Dialog box put it in the Temp folder and moved it at the end. Just think about it. If IE requires the file to be downloaded to the Temp folder, setting the Cache-Control and Pragma headers will cause an error!

I hope this saves someone some time!
~Cody G.

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scott at lucentminds dot com ¶

14 years ago

If you want to remove a header and keep it from being sent as part of the header response, just provide nothing as the header value after the header name. For example...

PHP, by default, always returns the following header:

"Content-Type: text/html"

Which your entire header response will look like

HTTP/1.1 200 OK
Server: Apache/2.2.11 (Unix)
X-Powered-By: PHP/5.2.8
Date: Fri, 16 Oct 2009 23:05:07 GMT
Content-Type: text/html; charset=UTF-8
Connection: close

If you call the header name with no value like so...

<?php

    header( 'Content-Type:' );

?>

Your headers now look like this:

HTTP/1.1 200 OK
Server: Apache/2.2.11 (Unix)
X-Powered-By: PHP/5.2.8
Date: Fri, 16 Oct 2009 23:05:07 GMT
Connection: close

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Anonymous ¶

14 years ago

I just want to add, becuase I see here lots of wrong formated headers.



1. All used headers have first letters uppercase, so you MUST follow this. For example:



Location, not location

Content-Type, not content-type, nor CONTENT-TYPE



2. Then there MUST be colon and space, like



good: header("Content-Type: text/plain");

wrong: header("Content-Type:text/plain");



3. Location header MUST be absolute uri with scheme, domain, port, path, etc.



good: header("Location: http://www.example.com/something.php?a=1");



4. Relative URIs are NOT allowed



wrong:  Location: /something.php?a=1

wrong:  Location: ?a=1



It will make proxy server and http clients happier.

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Vinay Kotekar ¶

9 years ago

Saving php file in ANSI  no isuess but when saving the file in UTF-8 format for various reasons remember to save the file without any BOM ( byte-order mark) support.
Otherwise you will face problem of headers not being properly sent 
eg. 
<?php header("Set-Cookie: name=user");?>

Would give something like this :-

Warning: Cannot modify header information - headers already sent by (output started at C:\www\info.php:1) in C:\www\info.php on line 1

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Angelica Perduta ¶

4 years ago

I made a script that generates an optimized image for use on web pages using a 404 script to resize and reduce original images, but on some servers it was generating the image but then not using it due to some kind of cache somewhere of the 404 status. I managed to get it to work with the following and although I don't quite understand it, I hope my posting here does help others with similar issues:

    header_remove();
    header("Cache-Control: no-store, no-cache, must-revalidate, max-age=0");
    header("Cache-Control: post-check=0, pre-check=0", false);
    header("Pragma: no-cache");
    // ... and then try redirecting
    // 201 = The request has been fulfilled, resulting in the creation of a new resource however it's still not loading
    // 302 "moved temporarily" does seems to load it!
    header("location:$dst", FALSE, 302); // redirect to the file now we have it

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bMindful at fleetingiamge dot org ¶

20 years ago

If you haven't used, HTTP Response 204 can be very convenient. 204 tells the server to immediately termiante this request. This is helpful if you want a javascript (or similar) client-side function to execute a server-side function without refreshing or changing the current webpage. Great for updating database, setting global variables, etc.



     header("status: 204");  (or the other call)

     header("HTTP/1.0 204 No Response");

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nobileelpirata at hotmail dot com ¶

16 years ago

This is the Headers to force a browser to use fresh content (no caching) in HTTP/1.0 and HTTP/1.1:



<?PHP

header( 'Expires: Sat, 26 Jul 1997 05:00:00 GMT' );

header( 'Last-Modified: ' . gmdate( 'D, d M Y H:i:s' ) . ' GMT' );

header( 'Cache-Control: no-store, no-cache, must-revalidate' );

header( 'Cache-Control: post-check=0, pre-check=0', false );

header( 'Pragma: no-cache' );



?>

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er dot ellison dot nyc at gmail dot com ¶

8 years ago

DO NOT PUT space between location and the colon that comes after that , 
// DO NOT USE THIS : 
header("Location : #whatever"); // -> will not work !

// INSTEAD USE THIS -> 
header("Location: #wahtever"); // -> will work forever !

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jamie ¶

15 years ago

The encoding of a file is discovered by the Content-Type, either in the HTML meta tag or as part of the HTTP header. Thus, the server and browser does not need - nor expect - a Unicode file to begin with a BOM mark. BOMs can confuse *nix systems too. More info at http://unicode.org/faq/utf_bom.html#bom1

On another note: Safari can display CMYK images (at least the OS X version, because it uses the services of QuickTime)

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ASchmidt at Anamera dot net ¶

5 years ago

Setting the "Location: " header has another undocumented side-effect! 

It will also disregard any expressly set "Content-Type: " and forces:

"Content-Type: text/html; charset=UTF-8"

The HTTP RFCs don't call for such a drastic action. They simply state that a redirect content SHOULD include a link to the destination page (in which case ANY HTML compatible content type would do). But PHP even overrides a perfectly standards-compliant 
"Content-Type: application/xhtml+xml"!

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hamza dot eljaouhari dot etudes at gmail dot com ¶

5 years ago

// Beware that adding a space between the keyword "Location" and the colon causes an Internal Sever Error

//This line causes the error
        7
header('Location : index.php&controller=produit&action=index');

// While It must be written without the space
 header('Location: index.php&controller=produit&action=index');

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cedric at gn dot apc dot org ¶

13 years ago

Setting a Location header "returns a REDIRECT (302) status code to the browser unless the 201 or a 3xx status code has already been set".  If you are sending a response to a POST request, you might want to look at RFC 2616 sections 10.3.3 and 10.3.4.   It is suggested that if you want the browser to immediately GET the resource in the Location header in this circumstance, you should use a 303 status code not the 302 (with the same link as hypertext in the body for very old browsers).  This may have (rare) consequences as mentioned in bug 42969.

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