PHP_SELF, PATH_INFO, SCRIPT_NAME, and REQUEST_URI: What\'s the Difference?

PHP_SELF vs PATH_INFO vs SCRIPT_NAME vs REQUEST_URI: Understanding the Differences

When developing PHP applications, it's crucial to understand the difference between PHP_SELF, PATH_INFO, SCRIPT_NAME, and REQUEST_URI. These server variables provide information about the current script's address and can be useful for navigation and URL rewriting.

PHP_SELF typically contains the full URI of the current script, including the script name and any path information. However, it can be different from SCRIPT_NAME in cases where the request is in the form of http://example.com/test.php/foo/bar.

PATH_INFO contains the path information at the end of the request URI. However, it's only populated when the request URI is in the form mentioned above.

SCRIPT_NAME represents the name of the current script, excluding any path information. It's usually the same as PHP_SELF unless there is a / in the URI.

REQUEST_URI contains the complete request URI, including the path, query string, and anchor. It differs from PHP_SELF and SCRIPT_NAME when a query string is present or when server-side redirection is used.

To illustrate the differences, here are some practical examples:

Example 1:
http://example.com/test.php/foo/bar

• PHP_SELF: /test.php/foo/bar
• SCRIPT_NAME: /test.php

Example 2:
http://example.com/test.php?foo=bar

• SCRIPT_NAME: /test.php
• REQUEST_URI: /test.php?foo=bar

Example 3:
http://example.com/test.php (with mod_rewrite redirect)

• REQUEST_URI: /test.php
• SCRIPT_NAME: /test2.php

Example 4:
Custom error page in IIS:
http://example.com/test.php

• SCRIPT_NAME: /404error.php
• REQUEST_URI: /404error.php?404;http://example.com/test.php

By understanding these differences, you can effectively utilize the appropriate server variable to handle navigation, URL rewriting, and error handling in your PHP applications.

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