1) $_SERVER['REQUEST_URI']
- It return the URL in to access the page which is executing the script. If you need to type http://www.example.com/product.php?id=5
to access the page then $_SERVER['REQUEST_URI']
returns /product.php?id=5
.
2) $_SERVER['DOCUMENT_ROOT']
– Returns the root directory of the server which is specified in the configuration file of server. This variable usually returns the path like /usr/yoursite/www
in Linux and D:/xamps/xampp/htdocs
in windows.
3) $_SERVER['HTTP_HOST']
– Returns the host’s name as found in the http header. This variable usually returns the path like example.com
when the you find http://example.com
in browser’s address-bar and return www.example.com
when you see http://www.example.com
in the address-bar. This is quite useful when you’ve to preserve session while making online payment using PHP since session stored for http://example.com
is not same as for the http://www.example.com
.
4) $_SERVER['HTTP_USER_AGENT']
- Returns the user agent’s (browser) detail accessing the web page. We can use strpos($_SERVER["HTTP_USER_AGENT"],”MSIE”)
to detect Microsoft Internet explorer or you can use strpos($_SERVER["HTTP_USER_AGENT"],”Firefox”)
to detect firefox browser in PHP.
5) $_SERVER['PHP_SELF']
- Returns the file-name of the currently executing script. Let’s suppose that you’re accessing the URL http://www.example.com/product.php?id=5
then $_SERVER['PHP_SELF']
returns /product.php
in your script.
6) $_SERVER['QUERY_STRING']
– Returns the query string if query string is used to access the script currently executing. Query strings are those string which is available after “?” sign.if you use $_SERVER['QUERY_STRING']
in the script executing the following URL http://www.example.com/index.php?id=5&page=product
then it returns id=5&page=product
in your script.
7) $_SERVER['REMOTE_ADDR']
– Returns the IP address of remote machine accessing the current page. But you can’t relie on $_SERVER['REMOTE_ADDR']
to get the real IP address of client’s machine. See this article to know how to get real IP addrees in PHP.
8 ) $_SERVER['SCRIPT_FILENAME']
- Returns the absolute path of the file which is currently executing. It returns path like var/example.com/www/product.php
in Linux and path like D:/xampp/xampp/htdocs/test/example.php
in windows.