Language Reference
PHP Manual

Predefined Variables

PHP provides a large number of predefined variables to all scripts. The variables represent everything from external variables to built-in environment variables, last error messages to last retrieved headers.

See also the FAQ titled "How does register_globals affect me?"

Superglobals

Superglobals are built-in variables that are always available in all scopes

Description

Several predefined variables in PHP are "superglobals", which means they are available in all scopes throughout a script. There is no need to do global $variable; to access them within functions or methods.

These superglobal variables are:

  • $GLOBALS
  • $_SERVER
  • $_GET
  • $_POST
  • $_FILES
  • $_COOKIE
  • $_SESSION
  • $_REQUEST
  • $_ENV

Changelog

Version Description
4.1.0 Superglobals were introduced to PHP.

Notes

Note: Variable availability

By default, all of the superglobals are available but there are directives that affect this availability. For further information, refer to the documentation for variables_order.

Note: Dealing with register_globals

If the deprecated register_globals directive is set to on then the variables within will also be made available in the global scope of the script. For example, $_POST['foo'] would also exist as $foo.

For related information, see the FAQ titled "How does register_globals affect me?"

Note: Variable variables

Superglobals cannot be used as variable variables inside functions or class methods.

$GLOBALS

References all variables available in global scope

Description

An associative array containing references to all variables which are currently defined in the global scope of the script. The variable names are the keys of the array.

Examples

Example #1 $GLOBALS example

<?php
function test() {
    $foo = "local variable";

    echo '$foo in global scope: ' . $GLOBALS["foo"] . "\n";
    echo '$foo in current scope: ' . $foo . "\n";
}

$foo = "Example content";
test();
?>

The above example will output something similar to:

$foo in global scope: Example content
$foo in current scope: local variable

Notes

Note:

This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. There is no need to do global $variable; to access it within functions or methods.

Note: Variable availability

Unlike all of the other superglobals, $GLOBALS has essentially always been available in PHP.

$_SERVER

$HTTP_SERVER_VARS [deprecated]

Server and execution environment information

Description

$_SERVER is an array containing information such as headers, paths, and script locations. The entries in this array are created by the web server. There is no guarantee that every web server will provide any of these; servers may omit some, or provide others not listed here. That said, a large number of these variables are accounted for in the » CGI/1.1 specification, so you should be able to expect those.

$HTTP_SERVER_VARS contains the same initial information, but is not a superglobal. (Note that $HTTP_SERVER_VARS and $_SERVER are different variables and that PHP handles them as such)

Indices

You may or may not find any of the following elements in $_SERVER. Note that few, if any, of these will be available (or indeed have any meaning) if running PHP on the command line.

'PHP_SELF'
The filename of the currently executing script, relative to the document root. For instance, $_SERVER['PHP_SELF'] in a script at the address http://example.com/foo/bar.php would be /foo/bar.php. The __FILE__ constant contains the full path and filename of the current (i.e. included) file. If PHP is running as a command-line processor this variable contains the script name since PHP 4.3.0. Previously it was not available.
'argv'
Array of arguments passed to the script. When the script is run on the command line, this gives C-style access to the command line parameters. When called via the GET method, this will contain the query string.
'argc'
Contains the number of command line parameters passed to the script (if run on the command line).
'GATEWAY_INTERFACE'
What revision of the CGI specification the server is using; i.e. 'CGI/1.1'.
'SERVER_ADDR'
The IP address of the server under which the current script is executing.
'SERVER_NAME'
The name of the server host under which the current script is executing. If the script is running on a virtual host, this will be the value defined for that virtual host.
'SERVER_SOFTWARE'
Server identification string, given in the headers when responding to requests.
'SERVER_PROTOCOL'
Name and revision of the information protocol via which the page was requested; i.e. 'HTTP/1.0';
'REQUEST_METHOD'
Which request method was used to access the page; i.e. 'GET', 'HEAD', 'POST', 'PUT'.

Note:

PHP script is terminated after sending headers (it means after producing any output without output buffering) if the request method was HEAD.

'REQUEST_TIME'
The timestamp of the start of the request. Available since PHP 5.1.0.
'REQUEST_TIME_FLOAT'
The timestamp of the start of the request, with microsecond precision. Available since PHP 5.4.0.
'QUERY_STRING'
The query string, if any, via which the page was accessed.
'DOCUMENT_ROOT'
The document root directory under which the current script is executing, as defined in the server's configuration file.
'HTTP_ACCEPT'
Contents of the Accept: header from the current request, if there is one.
'HTTP_ACCEPT_CHARSET'
Contents of the Accept-Charset: header from the current request, if there is one. Example: 'iso-8859-1,*,utf-8'.
'HTTP_ACCEPT_ENCODING'
Contents of the Accept-Encoding: header from the current request, if there is one. Example: 'gzip'.
'HTTP_ACCEPT_LANGUAGE'
Contents of the Accept-Language: header from the current request, if there is one. Example: 'en'.
'HTTP_CONNECTION'
Contents of the Connection: header from the current request, if there is one. Example: 'Keep-Alive'.
'HTTP_HOST'
Contents of the Host: header from the current request, if there is one.
'HTTP_REFERER'
The address of the page (if any) which referred the user agent to the current page. This is set by the user agent. Not all user agents will set this, and some provide the ability to modify HTTP_REFERER as a feature. In short, it cannot really be trusted.
'HTTP_USER_AGENT'
Contents of the User-Agent: header from the current request, if there is one. This is a string denoting the user agent being which is accessing the page. A typical example is: Mozilla/4.5 [en] (X11; U; Linux 2.2.9 i586). Among other things, you can use this value with get_browser to tailor your page's output to the capabilities of the user agent.
'HTTPS'
Set to a non-empty value if the script was queried through the HTTPS protocol.

Note: Note that when using ISAPI with IIS, the value will be off if the request was not made through the HTTPS protocol.

'REMOTE_ADDR'
The IP address from which the user is viewing the current page.
'REMOTE_HOST'
The Host name from which the user is viewing the current page. The reverse dns lookup is based off the REMOTE_ADDR of the user.

Note: Your web server must be configured to create this variable. For example in Apache you'll need HostnameLookups On inside httpd.conf for it to exist. See also gethostbyaddr.

'REMOTE_PORT'
The port being used on the user's machine to communicate with the web server.
'REMOTE_USER'
The authenticated user.
'REDIRECT_REMOTE_USER'
The authenticated user if the request is internally redirected.
'SCRIPT_FILENAME'

The absolute pathname of the currently executing script.

Note:

If a script is executed with the CLI, as a relative path, such as file.php or ../file.php, $_SERVER['SCRIPT_FILENAME'] will contain the relative path specified by the user.

'SERVER_ADMIN'
The value given to the SERVER_ADMIN (for Apache) directive in the web server configuration file. If the script is running on a virtual host, this will be the value defined for that virtual host.
'SERVER_PORT'
The port on the server machine being used by the web server for communication. For default setups, this will be '80'; using SSL, for instance, will change this to whatever your defined secure HTTP port is.

Note: Under the Apache 2, you must set UseCanonicalName = On, as well as UseCanonicalPhysicalPort = On in order to get the physical (real) port, otherwise, this value can be spoofed and it may or may not return the physical port value. It is not safe to rely on this value in security-dependent contexts.

'SERVER_SIGNATURE'
String containing the server version and virtual host name which are added to server-generated pages, if enabled.
'PATH_TRANSLATED'
Filesystem- (not document root-) based path to the current script, after the server has done any virtual-to-real mapping.

Note: As of PHP 4.3.2, PATH_TRANSLATED is no longer set implicitly under the Apache 2 SAPI in contrast to the situation in Apache 1, where it's set to the same value as the SCRIPT_FILENAME server variable when it's not populated by Apache. This change was made to comply with the CGI specification that PATH_TRANSLATED should only exist if PATH_INFO is defined. Apache 2 users may use AcceptPathInfo = On inside httpd.conf to define PATH_INFO.

'SCRIPT_NAME'
Contains the current script's path. This is useful for pages which need to point to themselves. The __FILE__ constant contains the full path and filename of the current (i.e. included) file.
'REQUEST_URI'
The URI which was given in order to access this page; for instance, '/index.html'.
'PHP_AUTH_DIGEST'
When doing Digest HTTP authentication this variable is set to the 'Authorization' header sent by the client (which you should then use to make the appropriate validation).
'PHP_AUTH_USER'
When doing HTTP authentication this variable is set to the username provided by the user.
'PHP_AUTH_PW'
When doing HTTP authentication this variable is set to the password provided by the user.
'AUTH_TYPE'
When doing HTTP authenticated this variable is set to the authentication type.
'PATH_INFO'
Contains any client-provided pathname information trailing the actual script filename but preceding the query string, if available. For instance, if the current script was accessed via the URL http://www.example.com/php/path_info.php/some/stuff?foo=bar, then $_SERVER['PATH_INFO'] would contain /some/stuff.
'ORIG_PATH_INFO'
Original version of 'PATH_INFO' before processed by PHP.

Changelog

Version Description
4.1.0 Introduced $_SERVER that deprecated $HTTP_SERVER_VARS.

Examples

Example #2 $_SERVER example

<?php
echo $_SERVER['SERVER_NAME'];
?>

The above example will output something similar to:

www.example.com

Notes

Note:

This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. There is no need to do global $variable; to access it within functions or methods.

$_GET

$HTTP_GET_VARS [deprecated]

HTTP GET variables

Description

An associative array of variables passed to the current script via the URL parameters.

$HTTP_GET_VARS contains the same initial information, but is not a superglobal. (Note that $HTTP_GET_VARS and $_GET are different variables and that PHP handles them as such)

Changelog

Version Description
4.1.0 Introduced $_GET that deprecated $HTTP_GET_VARS.

Examples

Example #3 $_GET example

<?php
echo 'Hello ' . htmlspecialchars($_GET["name"]) . '!';
?>

Assuming the user entered http://example.com/?name=Hannes

The above example will output something similar to:

Hello Hannes!

Notes

Note:

This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. There is no need to do global $variable; to access it within functions or methods.

Note:

The GET variables are passed through urldecode.

$_POST

$HTTP_POST_VARS [deprecated]

HTTP POST variables

Description

An associative array of variables passed to the current script via the HTTP POST method.

$HTTP_POST_VARS contains the same initial information, but is not a superglobal. (Note that $HTTP_POST_VARS and $_POST are different variables and that PHP handles them as such)

Changelog

Version Description
4.1.0 Introduced $_POST that deprecated $HTTP_POST_VARS.

Examples

Example #4 $_POST example

<?php
echo 'Hello ' . htmlspecialchars($_POST["name"]) . '!';
?>

Assuming the user POSTed name=Hannes

The above example will output something similar to:

Hello Hannes!

Notes

Note:

This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. There is no need to do global $variable; to access it within functions or methods.

$_FILES

$HTTP_POST_FILES [deprecated]

HTTP File Upload variables

Description

An associative array of items uploaded to the current script via the HTTP POST method.

$HTTP_POST_FILES contains the same initial information, but is not a superglobal. (Note that $HTTP_POST_FILES and $_FILES are different variables and that PHP handles them as such)

Changelog

Version Description
4.1.0 Introduced $_FILES that deprecated $HTTP_POST_FILES.

Notes

Note:

This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. There is no need to do global $variable; to access it within functions or methods.

See Also

$_REQUEST

HTTP Request variables

Description

An associative array that by default contains the contents of $_GET, $_POST and $_COOKIE.

Changelog

Version Description
5.3.0 Introduced request_order. This directive affects the contents of $_REQUEST.
4.3.0 $_FILES information was removed from $_REQUEST.
4.1.0 Introduced $_REQUEST.

Notes

Note:

This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. There is no need to do global $variable; to access it within functions or methods.

Note:

When running on the command line , this will not include the argv and argc entries; these are present in the $_SERVER array.

Note:

The variables in $_REQUEST are provided to the script via the GET, POST, and COOKIE input mechanisms and therefore could be modified by the remote user and cannot be trusted. The presence and order of variables listed in this array is defined according to the PHP variables_order configuration directive.

See Also

$_SESSION

$HTTP_SESSION_VARS [deprecated]

Session variables

Description

An associative array containing session variables available to the current script. See the Session functions documentation for more information on how this is used.

$HTTP_SESSION_VARS contains the same initial information, but is not a superglobal. (Note that $HTTP_SESSION_VARS and $_SESSION are different variables and that PHP handles them as such)

Changelog

Version Description
4.1.0 Introduced $_SESSION that deprecated $HTTP_SESSION_VARS.

Notes

Note:

This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. There is no need to do global $variable; to access it within functions or methods.

See Also

  • session_start

$_ENV

$HTTP_ENV_VARS [deprecated]

Environment variables

Description

An associative array of variables passed to the current script via the environment method.

These variables are imported into PHP's global namespace from the environment under which the PHP parser is running. Many are provided by the shell under which PHP is running and different systems are likely running different kinds of shells, a definitive list is impossible. Please see your shell's documentation for a list of defined environment variables.

Other environment variables include the CGI variables, placed there regardless of whether PHP is running as a server module or CGI processor.

$HTTP_ENV_VARS contains the same initial information, but is not a superglobal. (Note that $HTTP_ENV_VARS and $_ENV are different variables and that PHP handles them as such)

Changelog

Version Description
4.1.0 Introduced $_ENV that deprecated $HTTP_ENV_VARS.

Examples

Example #5 $_ENV example

<?php
echo 'My username is ' .$_ENV["USER"] . '!';
?>

Assuming "bjori" executes this script

The above example will output something similar to:

My username is bjori!

Notes

Note:

This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. There is no need to do global $variable; to access it within functions or methods.

See Also

$_COOKIE

$HTTP_COOKIE_VARS [deprecated]

HTTP Cookies

Description

An associative array of variables passed to the current script via HTTP Cookies.

$HTTP_COOKIE_VARS contains the same initial information, but is not a superglobal. (Note that $HTTP_COOKIE_VARS and $_COOKIE are different variables and that PHP handles them as such)

Changelog

Version Description
4.1.0 Introduced $_COOKIE that deprecated $HTTP_COOKIE_VARS.

Examples

Example #6 $_COOKIE example

<?php
echo 'Hello ' . htmlspecialchars($_COOKIE["name"]) . '!';
?>

Assuming the "name" cookie has been set earlier

The above example will output something similar to:

Hello Hannes!

Notes

Note:

This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. There is no need to do global $variable; to access it within functions or methods.

$php_errormsg

The previous error message

Description

$php_errormsg is a variable containing the text of the last error message generated by PHP. This variable will only be available within the scope in which the error occurred, and only if the track_errors configuration option is turned on (it defaults to off).

Warning

If a user defined error handler (set_error_handler) is set $php_errormsg is only set if the error handler returns FALSE.

Examples

Example #7 $php_errormsg example

<?php
@strpos();
echo $php_errormsg;
?>

The above example will output something similar to:

Wrong parameter count for strpos()

$HTTP_RAW_POST_DATA

Raw POST data

Description

$HTTP_RAW_POST_DATA contains the raw POST data. See always_populate_raw_post_data

$http_response_header

HTTP response headers

Description

The $http_response_header array is similar to the get_headers function. When using the HTTP wrapper, $http_response_header will be populated with the HTTP response headers. $http_response_header will be created in the local scope.

Examples

Example #8 $http_response_header example

<?php
function get_contents() {
  file_get_contents("http://example.com");
  var_dump($http_response_header);
}
get_contents();
var_dump($http_response_header);
?>

The above example will output something similar to:

array(9) {
  [0]=>
  string(15) "HTTP/1.1 200 OK"
  [1]=>
  string(35) "Date: Sat, 12 Apr 2008 17:30:38 GMT"
  [2]=>
  string(29) "Server: Apache/2.2.3 (CentOS)"
  [3]=>
  string(44) "Last-Modified: Tue, 15 Nov 2005 13:24:10 GMT"
  [4]=>
  string(27) "ETag: "280100-1b6-80bfd280""
  [5]=>
  string(20) "Accept-Ranges: bytes"
  [6]=>
  string(19) "Content-Length: 438"
  [7]=>
  string(17) "Connection: close"
  [8]=>
  string(38) "Content-Type: text/html; charset=UTF-8"
}
NULL

$argc

The number of arguments passed to script

Description

Contains the number of arguments passed to the current script when running from the command line.

Note: The script's filename is always passed as an argument to the script, therefore the minimum value of $argc is 1.

Note: This variable is not available when register_argc_argv is disabled.

Examples

Example #9 $argc example

<?php
var_dump($argc);
?>

When executing the example with: php script.php arg1 arg2 arg3

The above example will output something similar to:

int(4)

$argv

Array of arguments passed to script

Description

Contains an array of all the arguments passed to the script when running from the command line.

Note: The first argument $argv[0] is always the name that was used to run the script.

Note: This variable is not available when register_argc_argv is disabled.

Examples

Example #10 $argv example

<?php
var_dump($argv);
?>

When executing the example with: php script.php arg1 arg2 arg3

The above example will output something similar to:

array(4) {
  [0]=>
  string(10) "script.php"
  [1]=>
  string(4) "arg1"
  [2]=>
  string(4) "arg2"
  [3]=>
  string(4) "arg3"
}

See Also

  • getopt

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