$_SERVER

The $_SERVER is a superglobal in PHP. It includes information about HTTP headers, path, script location, and other things. It is an associative array that contains information about the execution environment and server.

The majority of these details are filled in by the web server and each server may have different entries. When running PHP scripts from the command line, some of these entries might not be available.

PHP also generates additional objects using request headers. The header name, which is in uppercase and has underscores instead of hyphens, is followed by the term “HTTP_” for these items.

Key Points about the $_SERVER

$_SERVER is a superglobal in PHP. It holds information regarding HTTP headers, path and script location, etc.

• $_SERVER is an associative array and it holds all the server and execution environment related information.
• Most of the entries in this associative array are populated by the web server. The entries may change from one web server to other, as servers may omit some, or provide others.
• For a PHP script running on the command line, most of these entries will not be available or have any meaning.
• PHP will also create additional elements with values from request headers. These entries will be named “HTTP_” followed by the header name, capitalized and with underscores instead of hyphens.
• For example, the “Accept-Language” header would be available as $_SERVER[‘HTTP_ACCEPT_LANGUAGE’].
• PHP versions prior to 5.4.0 had $HTTP_SERVER_VARS which contained the same information but it has now been removed.

Server Variables

The following table lists some of the important server variables of the $_SERVER array followed by the description of their values.

Sr.No	Server Variables & Description
1	PHP_SELFStores filename of currently executing script.
2	SERVER_ADDRThis property of array returns the IP address of the server under which the current script is executing.
3	SERVER_NAMEName of server host under which the current script is executing. In case of a server running locally, localhost is returned.
4	QUERY_STRINGA query string is the string of key value pairs separated by the “&” symbol and appended to the URL after the “?” symbol.For example, http://localhost/testscript?name=xyz&age=20 URL returns trailing query string
5	REQUEST_METHODHTTP request method used for accessing a URL, such as POST, GET, POST, PUT or DELETE.In the above query string example, a URL attached to query string with the “?” symbol requests the page with GET method
6	DOCUMENT_ROOTReturns the name of the directory on the server that is configured as the document root.On XAMPP apache server, it returns htdocs as the name of document root c:/xampp/htdocs
7	REMOTE_ADDRIP address of the machine from where the user is viewing the current page.
8	SERVER_PORTPort number on which the web server is listening to the incoming request. Default is 80
9	SCRIPT_FILENAMEThe absolute path to the currently executing script.
10	HTTP_HOSTThe contents of the Host header from the current request.
11	SCRIPT_NAMEContains the path of the current script relative to the document root.
12	REQUEST_URIThe URI that was given to access the page, including the query string.
13	HTTPSSet to ‘on’ if the request was made over HTTPS, otherwise not set.
14	SERVER_PROTOCOLThe name and version of the information protocol used, like HTTP/1.1 or HTTP/2.
15	GATEWAY_INTERFACEThe version of the CGI specification that the server uses, like CGI/1.1.

Example

The following script invoked from document root of XAMPP server lists all the server variables −

<?php
   foreach ($_SERVER as $k=>$v)
   echo $k . "=>" . $v . "\n";
?>

It will produce the following output −

MIBDIRS=>C:/xampp/php/extras/mibs
MYSQL_HOME=>\xampp\mysql\bin
OPENSSL_CONF=>C:/xampp/apache/bin/openssl.cnf
PHP_PEAR_SYSCONF_DIR=>\xampp\php
PHPRC=>\xampp\php
TMP=>\xampp\tmp
HTTP_HOST=>localhost
HTTP_CONNECTION=>keep-alive
HTTP_SEC_CH_UA=>"Chromium";v="116", "Not)
A;Brand";v="24", "Google Chrome";v="116"
HTTP_SEC_CH_UA_MOBILE=>?0
HTTP_SEC_CH_UA_PLATFORM=>"Windows"
HTTP_DNT=>1
HTTP_UPGRADE_INSECURE_REQUESTS=>1
HTTP_USER_AGENT=>Mozilla/5.0 (Windows NT 10.0; Win64; x64)
 AppleWebKit/537.36 (KHTML, like Gecko) Chrome/116.0.0.0 Safari/537.36
HTTP_ACCEPT=>text/html,application/xhtml+xml,application/xml;
q=0.9,image/avif,image/webp,image/apng,*/*;
q=0.8,application/signed-exchange;v=b3;q=0.7
HTTP_SEC_FETCH_SITE=>none
HTTP_SEC_FETCH_MODE=>navigate
HTTP_SEC_FETCH_USER=>?1
HTTP_SEC_FETCH_DEST=>document
HTTP_ACCEPT_ENCODING=>gzip, deflate, br
HTTP_ACCEPT_LANGUAGE=>en-US,en;q=0.9,mr;q=0.8
PATH=>C:\Python311\Scripts\;
C:\Python311\;C:\WINDOWS\system32;
C:\WINDOWS;C:\WINDOWS\System32\Wbem;
C:\WINDOWS\System32\WindowsPowerShell\v1.0\;
C:\WINDOWS\System32\OpenSSH\;C:\xampp\php;
C:\Users\user\AppData\Local\Microsoft\WindowsApps;
C:\VSCode\Microsoft VS Code\bin
SystemRoot=>C:\WINDOWS
COMSPEC=>C:\WINDOWS\system32\cmd.exe
PATHEXT=>.COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.MSC;.PY;.PYW
WINDIR=>C:\WINDOWS
SERVER_SIGNATURE=>
Apache/2.4.56 (Win64) OpenSSL/1.1.1t PHP/8.0.28 Server at localhost Port 80

SERVER_SOFTWARE=>Apache/2.4.56 (Win64) OpenSSL/1.1.1t PHP/8.0.28
SERVER_NAME=>localhost
SERVER_ADDR=>::1
SERVER_PORT=>80
REMOTE_ADDR=>::1
DOCUMENT_ROOT=>C:/xampp/htdocs
REQUEST_SCHEME=>http
CONTEXT_PREFIX=>
CONTEXT_DOCUMENT_ROOT=>C:/xampp/htdocs
SERVER_ADMIN=>postmaster@localhost
SCRIPT_FILENAME=>C:/xampp/htdocs/hello.php
REMOTE_PORT=>54148
GATEWAY_INTERFACE=>CGI/1.1
SERVER_PROTOCOL=>HTTP/1.1
REQUEST_METHOD=>GET
QUERY_STRING=>
REQUEST_URI=>/hello.php
SCRIPT_NAME=>/hello.php
PHP_SELF=>/hello.php
REQUEST_TIME_FLOAT=>1694802456.9816
REQUEST_TIME=>1694802456