Some useful server variables available in PHP
Server Variables are those variables which are inside the super global array named $_SERVER available in PHP. There are many server variables in PHP and some of them are very useful for fore developing PHP projects. The following are the server variables:-
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=10 to access the page then $_SERVER['REQUEST_URI'] returns “/product.php?id=10.
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=10 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=10&page=product” then it returns “id=10&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.
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=10 to access the page then $_SERVER['REQUEST_URI'] returns “/product.php?id=10.
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=10 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=10&page=product” then it returns “id=10&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.
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