Usage of PHP header() function (301, 404 and other error settings)

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

For the ErrorDocument 404 /404.php function in the apache configuration, change the ErrorDocument 404 /404.php function in the nginx configuration

error_page 404 /404.php;

and change it to

error_page 404 = /404.php;

php header 301

header("HTTP/1.1 301 Moved Permanently");
header ("Location:$url");
?>

No matter how many pages there are header, it will execute the last one, but conditionally, for example:

header('Location:http://bbs.it-home.org');
header('Location:http://www.g.cn');
header('Location:http ://www.baidu.com');

This will jump to Baidu

header('Location:http://bbs.it-home.org');echo 'Programmer's Home;
header('Location:http://www.g.cn');
header('Location:http://www.baidu.com');

This will jump to google Detailed instructions for using the header function 1. Function: PHP only sends the header of the HTML document to the browser using the HTTP protocol and tells the browser how to process the page. As for the transmitted content, you need to be familiar with the HTTP protocol and has nothing to do with PHP. Traditional headers must contain one of the following three headers and can only appear once.

 Redirect function, this is the most common

Header("Location: http://bbs.it-home.org/");
?>

Forces users to get the latest information every time they visit this page, instead of using the client-side cache.

//Tell the browser the expiration time of this page (expressed in Greenwich Mean Time), as long as it is a date that has passed.
header("Expires: Mon, 26 Jul 1970 05:00:00 GMT");
//Tell the browser the last updated date of this page (expressed in Greenwich Mean Time), which is the same day, the purpose is to force the browser to obtain Latest information
header("Last-Modified: " . gmdate("D, d M Y H:i:s") . "GMT");
//Tell the client browser not to use cache
header("Cache-Control: no-cache, must-revalidate");
//Parameters (compatible with previous servers), that is, compatible with HTTP1.0 protocol
header("Pragma: no-cache");
//Output MIME type
header(" Content-type: application/file");
//File length
header("Content-Length: 227685");
//Accepted range units
header("Accept-Ranges: bytes");
//Missing Time-saving file name in the file saving dialog box
header("Content-Disposition: attachment; filename=$filename");
?>

Output status value to the browser, mainly used Access control

header('HTTP/1.1 401 Unauthorized');
header('status: 401 Unauthorized');
?>

For example, to restrict a user If you cannot access the page, you can set the status to 404, as shown below, so that the browser will display that the page does not exist.

header('HTTP/1.1 404 Not Found');
header("status: 404 Not Found");
?>

Note: Traditional The header must contain one of the following three headers and can only appear once. Content-Type: xxxx/yyyy Location: xxxx:yyyy/zzzz Status: nnn xxxxxx can appear more than twice in the new multipart header specification (Multipart MIME).

Usage examples Example 1: This example redirects the browser to the official website of PHP.

Header("Location: http://bbs.it-home.org/"); exit;

Example 2: If you want users to get the latest data every time, instead of the data in the Proxy or cache, you can use the following headers

header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");
header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT"); header("Cache-Control: no-cache, must-revalidate");
header("Pragma: no-cache");

Example 3: Let the user's browser A message that the file cannot be found appears.

header("Status: 404 Not Found");

Example 4: Let users download files.

header("Content-type: application/x-gzip");
header("Content-Disposition: attachment; filename=filename");
header("Content-Description: PHP3 Generated Data" );

header -- Send a raw HTTP header description void header ( string string [, bool replace [, int http_response_code]] )

The

header() function is used to send a raw HTTP header. See the HTTP/1.1 specification for more information on HTTP headers. The optional parameter replace specifies whether to replace the previous similar header or add a header of the same type. The default is replacement, but setting it to FALSE can force multiple headers of the same type to be sent. For example:

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

Second The optional parameter http_response_code forces the HTTP response code to the specified value (this parameter is new in PHP 4.3.0).

There are two special header calls. The first is a header that begins with the string "HTTP/" (case is not important), which can be used to determine the HTTP status code to be sent. For example, if you configure Apache to use PHP to handle error-handling requests for file not found (using the ErrorDocument directive), you need to ensure that the script generates the correct status code.

　header("HTTP/1.0 404 Not Found")
?>

Note: The HTTP status code header line is always the first one sent to client, regardless of whether the actual header() call is the first one. Unless HTTP headers have already been sent, they can be overwritten at any time by calling the header() function with a new status line.

HTTP status detection (HTTP Header):

The second special case is the "Location:" header. It doesn't just send this header back to the browser, it also returns a REDIRECT (302) status code to the browser, unless a 3xx status code has been issued previously.

　header("Location: http://www.example.com/"); /* Redirect browser*/
　 /* Ensure that after redirection, subsequent code will not be Execute */
　Exit;
?>

Note: The HTTP/1.1 standard requires an absolute address URI as the Location: parameter, but some clients support relative URIs. You can usually use the $_SERVER['HTTP_HOST'], $_SERVER['PHP_SELF'] and dirname() functions to generate absolute URIs from relative URIs yourself:

　header("Location: http://%22.$_server['http_host'/]
　. rtrim(dirname($_SERVER['PHP_SELF']), '/\' )
　　."/".$relative_url);
?>

Note: Even if session.use_trans_sid is enabled, the Session ID will not be passed along with the Location header information. Must be passed manually as SID constant. ​ PHP scripts often produce dynamic content that must not be cached by browsers or proxy servers. Many proxy servers and browsers can disable caching by: Note: You may find that even without outputting all the code above, the web page is not buffered. There are many options that users can set to change the browser's default caching behavior. By sending the above headers, it should be possible to override any settings that could cause script pages to be cached. ​ Additionally, when sessions are used, the session_cache_limiter() function and the session.cache_limiter option can be used to automatically generate the correct cache-related headers. ​ Remember that header() must be called before any actual output, whether from regular HTML markup, blank lines or PHP. A common mistake is that when reading code through include(), require() or some other file access function, some spaces or empty lines are sent before calling header(). This error is also common in a single PHP/HTML file.

　header("Cache-Control: no-cache, must-revalidate"); // HTTP/1.1
header("Expires: Mon, 26 Jul 1997 05:00:00 GMT "); // Past time
?>

/* This will generate an error because the output has been output before calling header()
　* Got something*/
　header('Location: http://www.example.com/');
?>

Note: Since PHP 4, this can be solved by some output buffering functions this problem. The cost is that all output to the browser is cached on the server until a command is issued to send it. You can use ob_start() and ob_end_flush() in the code to achieve this function, or by modifying the output_buffering configuration option in php.ini, or by modifying the server configuration file.

Attached are two common uses of header():

//Set page encoding:
header('Content-Type: text/html;charset=gb2312');
//Adjust page:
header('location:http://www.baidu. com');