The purpose of getenv function in PHP_PHP tutorial-PHP Tutorial-php.cn

The purpose of getenv function in PHP_PHP tutorial

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Release： 2016-07-13 17:44:28

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In PHP, the getenv (parameter) function is a function used to obtain environment variables. Different environment variables can be obtained according to different parameters provided, as follows:

"PHP_SELF"
The file name of the currently executing script, relative to the document root. For example, using $_SERVER['PHP_SELF'] in a script with the URL address [url]http://example.com/test.php/foo.bar[/url] will result in /test.php/foo .bar the result. The __FILE__ constant contains the absolute path and file name of the current (i.e. containing) file.

If PHP is run from the command line, this variable has no effect prior to PHP 4.3.0.

"argv"
Parameters passed to this script. When the script is run in command-line mode, the argv variable is passed to the program as C-style command-line arguments. When the GET method is called, this variable contains the requested data.

"argc"
Contains the number of command line arguments passed to the program (if running in command line mode).

"GATEWAY_INTERFACE"
The version of the CGI specification used by the server. For example, "CGI/1.1".

"SERVER_NAME"
The name of the server host where the script is currently running. If the script is running on a virtual host, the name is determined by the value set for that virtual host.

"SERVER_SOFTWARE"
A string identifying the server, as given in the header of the response to the request.

"SERVER_PROTOCOL"
The name and version of the communication protocol used when requesting the page. For example, "HTTP/1.0".

"REQUEST_METHOD"
The request method when accessing the page. For example: "GET", "HEAD", "POST", "PUT".

Note: If the request method is HEAD, the PHP script will abort after sending the header information (this means that after any output is produced, there is no more output buffering).

"REQUEST_TIME"
The timestamp when the request started. Valid since PHP 5.1.0.

"QUERY_STRING"
The string of the query (the content after the first question mark ? in the URL).

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

"HTTP_ACCEPT"
The contents of the Accept: header of the current request.

"HTTP_ACCEPT_CHARSET"
The contents of the Accept-Charset: header of the current request. For example: "iso-8859-1,*,utf-8".

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

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

"HTTP_CONNECTION"
The contents of the Connection: header of the current request. For example: "Keep-Alive".

"HTTP_HOST"
The contents of the Host: header of the current request.

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

"HTTP_USER_AGENT"
The contents of the User-Agent: header of the current request. This string indicates information about the user agent accessing this page. A typical example is: Mozilla/4.5 [en] (X11; U; Linux 2.2.9 i586). This information can also be obtained using get_browser().

"HTTPS"
Set to a non-empty value if the script is accessed via the HTTPS protocol.

"REMOTE_ADDR"
The IP address of the user who is browsing the current page.

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

NOTE: The web server must be configured to establish this variable. For example Apache requires HostnameLookups On in httpd.conf. See gethostbyaddr().

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

"SCRIPT_FILENAME"
The absolute pathname of the currently executing script.

Note: If the script is executed from the CLI, as a relative path, such as file.php or ../file.php, $_SERVER['SCRIPT_FILENAME'] will contain the user-specified relative path.

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

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

"SERVER_SIGNATURE"
A string containing the server version and virtual hostname.

"PATH_TRANSLATED"
The base path of the file system (not the document root) where the current script is located. This is the result after the server has been imaged from a virtual to real path.

Note: After PHP 4.3.2, PATH_TRANSLATED in Apache 2 SAPI mode is no longer implicitly assigned like Apache 1. Instead, if Apache does not generate this value, PHP will generate it itself and put its value into the SCRIPT_FILENAME server constant. This modification adheres to the CGI specification, which states that PATH_TRANSLATED only exists if PATH_INFO is defined.

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

"SCRIPT_NAME"
Contains the path to 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 (such as an include file).

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

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

"PHP_AUTH_USER"
When PHP is running in Apache or IIS (PHP 5 is ISAPI) module mode and HTTP authentication is being used, this variable is the username entered by the user.

"PHP_AUTH_PW"
When PHP is running in Apache or IIS (PHP 5 is ISAPI) module mode and HTTP authentication is being used, this variable is the password entered by the user.