Usage of the getenv function in PHP

In PHP, The getenv (parameter) function is a function used to obtain environment variables. Different environment variables can be obtained based on different parameters. The details are as follows:

"PHP_SELF"
The file name of the script being executed, which is related to document root. For example, you can use $ _ SERVER ['php _ SELF '] in the script with the URL [url] http://example.com/test.php/foo.bar#/url] to obtain the result of/test. PHP/foo. bar. The _ FILE _ constant contains the absolute path and FILE name of the current (such as include) FILE.

If PHP runs as a command line, this variable is invalid before PHP 4.3.0.

"Argv"
Parameters passed to the script. When the script runs in the command line mode, the argv variable is passed to the command line parameters in the C language style of the program. When the GET method is called, the variable contains the requested data.

"Argc"
Contains the number of command line parameters passed to the Program (if it is in command line mode ).

"GATEWAY_INTERFACE"
The CGI Specification Version Used by the server. For example, "CGI/1.1 ".

"SERVER_NAME"
Name of the server host where the script is currently running. If the script runs on a VM, the name is determined by the value set by that VM.

"SERVER_SOFTWARE"
The string identified by the server, which is provided in the header information in the Response Request.

"SERVER_PROTOCOL"
The name and version of the communication protocol on the request page. For example, "HTTP/1.0 ".

"REQUEST_METHOD"
The request method used to access the page. For example, "GET", "HEAD", "POST", and "PUT ".

Note: If the request method is HEAD, the PHP script will stop sending the header information (this means no output buffer is available after any output is generated ).

"REQUEST_TIME"
The start time of the request. Valid from PHP 5.1.0.

"QUERY_STRING"
Query string (the first question mark in the URL? ).

"DOCUMENT_ROOT"
The document root directory where the script is currently running. Defined in the server configuration file.

"HTTP_ACCEPT"
The Accept of the current request: the content of the header information.

"HTTP_ACCEPT_CHARSET"
The Accept-Charset of the current request: the content of the header information. Example: "iso-8859-1, *, UTF-8 ".

"HTTP_ACCEPT_ENCODING"
The Accept-Encoding of the current request: the content of the header information. For example, "gzip ".

"HTTP_ACCEPT_LANGUAGE"
The Accept-Language of the current request: the content of the header information. For example, "en ".

"HTTP_CONNECTION"
Connection of the current request: header information. For example, "Keep-Alive ".

"HTTP_HOST"
Host of the current request: header information.

"HTTP_REFERER"
The URL of the previous page that is linked to the current page. Not all user proxies (browsers) will set this variable, and some can also manually modify HTTP_REFERER. Therefore, this variable is not always true and correct.

"HTTP_USER_AGENT"
User-Agent of the current request: header information. This string indicates the information of the User Agent accessing the page. A typical example is Mozilla/4.5 [en] (X11; U; Linux 2.2.9 i586 ). You can also use get_browser () to obtain this information.

"HTTPS"
If the script is accessed through the HTTPS protocol, it is set to a non-null value.

"REMOTE_ADDR"
Browsing the IP address of the user on the current page.

"REMOTE_HOST"
The host name of the user browsing the current page. Reverse Domain name resolution is based on the user's REMOTE_ADDR.

Note: You must configure the Web server to create this variable. For example, Apache needs to include HostnameLookups On in httpd. conf. See gethostbyaddr ().

"REMOTE_PORT"
The port used by the user to connect to the server.

"SCRIPT_FILENAME"
The absolute path name of the currently executed script.

Note: If the script is executed in CLI, it is used as a relative path, such as file. php or .. /file. php, $ _ SERVER ['script _ filename'] will contain the relative path specified by the user.

"SERVER_ADMIN"
This value specifies the SERVER_ADMIN parameter in the Apache server configuration file. If the script runs on a VM, this value is the value of that VM.

"SERVER_PORT"
The port used by the server. The default value is "80 ". If SSL secure connection is used, this value is the HTTP port set by the user.

"SERVER_SIGNATURE"
A string containing the server version and virtual host name.

"PATH_TRANSLATED"
The basic path of the file system (not the document root directory) where the current script is located. This is the result of a virtual image to a real path on the server.

Note: After PHP 4.3.2, PATH_TRANSLATED does not implicitly assign values like Apache 1 in Apache 2 SAPI mode. If Apache does not generate this value, PHP generates and puts the value in the SCRIPT_FILENAME server constant. This modification complies with CGI specifications. PATH_TRANSLATED exists only under the conditions defined by PATH_INFO.

Apache 2 users can use AcceptPathInfo On in httpd. conf to define PATH_INFO.

"SCRIPT_NAME"
The path that contains the current script. This is useful when the page needs to point to itself. _ FILE _ contains the absolute path and FILE name of the current FILE (for example, including the FILE ).

"REQUEST_URI"
The URI required to access this page. For example, "/index.html ".

"PHP_AUTH_DIGEST"
When running as an Apache module and performing HTTP Digest authentication, this variable is set to the "Authorization" HTTP header content sent by the client (For further authentication ).

"PHP_AUTH_USER"
When PHP runs in the Apache or IIS (PHP 5 is an ISAPI) module and is using the HTTP authentication function, this variable is the user input username.

"PHP_AUTH_PW"
When PHP runs in the Apache or IIS (PHP 5 is an ISAPI) module and is using the HTTP authentication function, this variable is the password entered by the user.