7.3. Server Information
The $_SERVER
array contains a lot of useful information from the web server. Much
of this information comes from the environment variables required in
the CGI
specification (http://hoohoo.ncsa.uiuc.edu/cgi/env.html).
Here is a complete list of the entries in $_SERVER
that come from CGI:
- SERVER_SOFTWARE
-
A string that identifies the server (e.g.,
"Apache/1.3.22 (Unix) mod_perl/1.26
PHP/4.1.0").
- SERVER_NAME
-
The hostname, DNS alias, or IP address for self-referencing URLs
(e.g., "www.example.com").
- GATEWAY_INTERFACE
-
The version of the CGI standard being followed (e.g.,
"CGI/1.1").
- SERVER_PROTOCOL
-
The name and revision of the request protocol (e.g.,
"HTTP/1.1").
- SERVER_PORT
-
The server port number to which the request was sent (e.g.,
"80").
- REQUEST_METHOD
-
The method the client used to fetch the document (e.g.,
"GET").
- PATH_INFO
-
Extra path elements given by the client (e.g.,
"/list/users").
- PATH_TRANSLATED
-
The value of PATH_INFO, translated by the server
into a filename (e.g.,
"/home/httpd/htdocs/list/users").
- SCRIPT_NAME
-
The URL path to the current page, which is useful for
self-referencing scripts (e.g.,
"/~me/menu.php").
- QUERY_STRING
-
Everything after the ? in the URL (e.g.,
"name=Fred+age=35").
- REMOTE_HOST
-
The hostname of the machine that requested this page (e.g.,
"dialup-192-168-0-1.example.com").
If there's no DNS for the machine, this is blank and
REMOTE_ADDR is the only information given.
- REMOTE_ADDR
-
A string containing the IP address of the machine that requested this
page (e.g., "192.168.0.250").
- AUTH_TYPE
-
If the page is password-protected, this is the authentication method
used to protect the page (e.g.,
"basic").
- REMOTE_USER
-
If the page is password-protected, this is the username with which
the client authenticated (e.g.,
"fred"). Note that
there's no way to find out what password was used.
- REMOTE_IDENT
-
If the server is configured to use identd (RFC
931) identification checks, this is the username fetched from the
host that made the web request (e.g.,
"barney"). Do not use this string
for authentication purposes, as it is easily spoofed.
- CONTENT_TYPE
-
The content type of the information attached to queries such as PUT
and POST (e.g., "x-url-encoded").
- CONTENT_LENGTH
-
The length of the information attached to queries such as PUT and
POST (e.g., 3952).
The Apache server also creates entries in the
$_SERVER
array for each HTTP
header in the request. For each key, the header name is converted to
uppercase, hyphens (-) are turned into underscores
(_), and the string "HTTP_" is
prepended. For example, the entry for the User-Agent header has the
key "HTTP_USER_AGENT". The two most common and
useful headers are:
- HTTP_USER_AGENT
-
The string the browser used to identify itself (e.g.,
"Mozilla/5.0 (Windows 2000; U) Opera 6.0
[en]")
- HTTP_REFERER
-
The page the browser said it came from to get to the current page
(e.g.,
"http://www.example.com/last_page.html")
 |  |  |
| 7.2. Variables |  | 7.4. Processing Forms |
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