Nginx built-in Variables

Nginx built-in Variable list, which extracts Nginx built-in variables according to nginx source code file ngx_http_variables.c.
According to different versions, the variables may change, and most of them can still be used.

Name	Version	Description (the Variable list is from the ngx_http_variables file)
$ Args	1.0.8	Parameters in the request;
$ Binary_remote_addr	1.0.8	Binary representation of remote addresses
$ Body_bytes_sent	1.0.8	Number of sent message body bytes
$ Content_length	1.0.8	"Content-Length" in the HTTP request information ";
$ Content_type	1.0.8	"Content-Type" in the request information ";
$ Document_root	1.0.8	Set the value for the root path of the current request;
$ Document_uri	1.0.8	Same as $ uri;
$ Host	1.0.8	"Host" in the request information. If the request does not contain the Host line, it is equal to the configured server name;
$ Hostname	1.0.8
$ Http_cookie	1.0.8	Cookie Information
$ Http_post	1.0.8
$ Http_referer	1.0.8	Reference address
$ Http_user_agent	1.0.8	Client Proxy Information
$ Http_via	1.0.8	The IP address of the last access server. Http://www.cnblogs.com/deng02/archive/2009/02/11/1387911.html
$ Http_x_forwarded_for	1.0.8	It is equivalent to the network access path. Http://www.cnblogs.com/craig/archive/2008/11/18/1335809.html
$ Is_args	1.0.8
$ Limit_rate	1.0.8	Restrictions on connection speed;
$ Nginx_version	1.0.8
$ Pid	1.0.8
$ Query_string	1.0.8	Same as $ args;
$ Realpath_root	1.0.8
$ Remote_addr	1.0.8	Client address;
$ Remote_port	1.0.8	Client port number;
$ Remote_user	1.0.8	Client user name, used for authentication;
$ Request	1.0.8	User request
$ Request_body	1.0.8
$ Request_body_file	1.0.8	Name of the local file sent to the backend
$ Request_completion	1.0.8
$ Request_filename	1.0.8	File Path Name of the current request
$ Request_method	1.0.8	Request methods, such as "GET" and "POST;
$ Request_uri	1.0.8	The requested URI with parameters;
$ Scheme	1.0.8	The protocol used, such as http or https, such as rewrite ^ (. +) $ scheme: // example.com $1 redirect;
$ Sent_http_cache_control	1.0.8
$ Sent_http_connection	1.0.8
$ Sent_http_content_length	1.0.8
$ Sent_http_content_type	1.0.8
$ Sent_http_keep_alive	1.0.8
$ Sent_http_last_modified	1.0.8
$ Sent_http_location	1.0.8
$ Sent_http_transfer_encoding	1.0.8
$ Server_addr	1.0.8	Server address. If you do not use listen to specify the server address, using this variable will initiate a system call to obtain the address (resulting in a waste of resources );
$ Server_name	1.0.8	The name of the server to which the request arrives;
$ Server_port	1.0.8	The Port Number of the server to which the request arrives;
$ Server_protocol	1.0.8	Request Protocol version, "HTTP/1.0" or "HTTP/1.1 ";
$ Uri	1.0.8	The requested URI may be different from the original value, for example, after redirection