What are the php environment variables?

php environment variables include $_SERVER['PHP_SELF'], $_SERVER['SERVER_NAME'], $_SERVER['QUERY_STRING'], $_SERVER['HTTP_REFERER'], $_SERVER['HTTP_USER_AGENT'], $_SERVER['REMOTE_ADDR'], $_SERVER['REQUEST_METHOD'], etc.

The operating environment of this tutorial: windows10 system, php8.1.3 version, DELL G3 computer.

PHP environment variables are a set of global variables used during PHP running. These variables contain some important information, such as file paths, server information, etc. This article will introduce some common PHP environment variables and their functions.

1. $_SERVER['PHP_SELF']:

This variable contains the path and file name of the script file currently being executed. It can be used to build dynamic links and redirects.

2. $_SERVER['SERVER_NAME']:

This variable contains the name or IP address of the current host. It can be used to build hostname-based processing logic, such as multiple domain names sharing the same code base.

3. $_SERVER['QUERY_STRING']:

This variable contains the query string in the request URL. It can be used to obtain parameter values ​​passed to the script via GET.

4. $_SERVER['HTTP_REFERER']:

This variable contains the URL that guides the user to access the current page. It can be used to detect which page the user jumped from.

5. $_SERVER['HTTP_USER_AGENT']:

This variable contains the user agent information that initiated the current request, such as the browser identification. It can be used to identify different types of user access.

6. $_SERVER['REMOTE_ADDR']:

This variable contains the IP address of the client that initiated the current request. It can be used to record the user's origin geographical location or do some security verification.

7. $_SERVER['REQUEST_METHOD']:

This variable contains the current request method, such as GET, POST, PUT, etc. It can be used to identify different types of requests and handle them accordingly.

8. $_SERVER['REQUEST_URI']:

This variable contains the URI address of the current request. It can be used to get the full URL path of the current script.

9. $_SERVER['HTTPS']:

This variable can determine whether the current request passes the HTTPS protocol. It can be used to force redirect user requests to HTTPS links.

10. $_SERVER['HTTP_HOST']:

This variable contains the name of the host that initiated the current request. It can be used to perform different logic based on the hostname.

In addition to the above environment variables, PHP also provides some other global variables, such as $_COOKIE, $_GET, $_POST, etc., for processing request-related data. These variables are usually used to receive user input data or pass data to other pages.

To summarize, PHP environment variables are global variables provided during PHP running and contain some important information. Proper use of these variables can make it easier for developers to handle request-related tasks and improve application performance and reliability. .

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