Since PHP 4.1.0, the preferred method for retrieving external variables is with the superglobals mentioned below. Before this time, people relied on either register_globals or the long predefined PHP arrays ($HTTP_*_VARS). As of PHP 5.0.0, the long PHP predefined variable arrays may be disabled with the register_long_arrays directive.
Note: Introduced in 4.1.0. In earlier versions, use $HTTP_SERVER_VARS.
$_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.
This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. You don't need to do a global $_SERVER; to access it within functions or methods, as you do with $HTTP_SERVER_VARS.
$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)
If the register_globals directive is set, then these variables will also be made available in the global scope of the script; i.e., separate from the $_SERVER and $HTTP_SERVER_VARS arrays. For related information, see the security chapter titled Using Register Globals. These individual globals are not superglobals.
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.
Note: PHP script is terminated after sending headers (it means after producing any output without output buffering) if the request method was HEAD.
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().
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.
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.
Note: Introduced in 4.1.0. In earlier versions, use $HTTP_ENV_VARS.
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.
This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. You don't need to do a global $_ENV; to access it within functions or methods, as you do with $HTTP_ENV_VARS.
$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)
If the register_globals directive is set, then these variables will also be made available in the global scope of the script; i.e., separate from the $_ENV and $HTTP_ENV_VARS arrays. For related information, see the security chapter titled Using Register Globals. These individual globals are not superglobals.
Note: Introduced in 4.1.0. In earlier versions, use $HTTP_GET_VARS.
An associative array of variables passed to the current script via the HTTP GET method. Automatically global in any scope.
This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. You don't need to do a global $_GET; to access it within functions or methods, as you do with $HTTP_GET_VARS.
$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)
If the register_globals directive is set, then these variables will also be made available in the global scope of the script; i.e., separate from the $_GET and $HTTP_GET_VARS arrays. For related information, see the security chapter titled Using Register Globals. These individual globals are not superglobals.
Note: Introduced in 4.1.0. In earlier versions, use $HTTP_POST_VARS.
An associative array of variables passed to the current script via the HTTP POST method. Automatically global in any scope.
This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. You don't need to do a global $_POST; to access it within functions or methods, as you do with $HTTP_POST_VARS.
$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)
If the register_globals directive is set, then these variables will also be made available in the global scope of the script; i.e., separate from the $_POST and $HTTP_POST_VARS arrays. For related information, see the security chapter titled Using Register Globals. These individual globals are not superglobals.
Note: Introduced in 4.1.0. In earlier versions, use $HTTP_POST_FILES.
An associative array of items uploaded to the current script via the HTTP POST method. Automatically global in any scope.
This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. You don't need to do a global $_FILES; to access it within functions or methods, as you do with $HTTP_POST_FILES.
$HTTP_POST_FILES contains the same information, but is not a superglobal. (Note that $HTTP_POST_FILES and $_FILES are different variables and that PHP handles them as such)
If the register_globals directive is set, then these variables will also be made available in the global scope of the script; i.e., separate from the $_FILES and $HTTP_POST_FILES arrays. For related information, see the security chapter titled Using Register Globals. These individual globals are not superglobals.
Note: Introduced in 4.1.0. There is no equivalent array in earlier versions.
Note: Prior to PHP 4.3.0, $_FILES information was also included in $_REQUEST.
An associative array consisting of the contents of $_GET, $_POST, and $_COOKIE.
This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. You don't need to do a global $_REQUEST; to access it within functions or methods.
If the register_globals directive is set, then these variables will also be made available in the global scope of the script; i.e., separate from the $_REQUEST array. For related information, see the security chapter titled Using Register Globals. These individual globals are not superglobals.
Note: Introduced in 4.1.0. In earlier versions, use $HTTP_SESSION_VARS.
An associative array containing session variables available to the current script. See the Session functions documentation for more information on how this is used.
This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. You don't need to do a global $_SESSION; to access it within functions or methods, as you do with $HTTP_SESSION_VARS.
$HTTP_SESSION_VARS contains the same information, but is not a superglobal. (Note that $HTTP_SESSION_VARS and $_SESSION are different variables and that PHP handles them as such)
If the register_globals directive is set, then these variables will also be made available in the global scope of the script; i.e., separate from the $_SESSION and $HTTP_SESSION_VARS arrays. For related information, see the security chapter titled Using Register Globals. These individual globals are not superglobals.
Note: $GLOBALS has been available since PHP 3.0.0.
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.
This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. You don't need to do a global $GLOBALS; to access it within functions or methods.
$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).
$HTTP_RAW_POST_DATA contains the raw POST data. See always_populate_raw_post_data
The $http_response_header array is similiar to the get_headers() function. When using the HTTP wrapper $http_response_header will be populated with the HTTP response headers.