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>Chapter 7. Variables</TD
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><DIV
CLASS="sect1"
><H1
CLASS="sect1"
><A
NAME="language.variables.predefined"
>Predefined variables</A
></H1
><P
> PHP provides a large number of predefined variables to any script
which it runs. Many of these variables, however, cannot be fully
documented as they are dependent upon which server is running, the
version and setup of the server, and other factors. Some of these
variables will not be available when PHP is run on the
command-line.
</P
><P
> Despite these factors, here is a list of predefined variables
available under a stock installation of PHP 3 running as a module
under a stock installation of <A
HREF="http://www.apache.org/"
TARGET="_top"
>Apache</A
> 1.3.6.
</P
><P
> For a list of all predefined variables (and lots of other useful
information), please see (and use) <A
HREF="function.phpinfo.html"
><B
CLASS="function"
>phpinfo()</B
></A
>.
</P
><DIV
CLASS="note"
><BLOCKQUOTE
CLASS="note"
><P
><B
>Note: </B
>
This list is neither exhaustive nor intended to be. It is simply
a guideline as to what sorts of predefined variables you can
expect to have access to in your script.
</P
></BLOCKQUOTE
></DIV
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="language.variables.predefined.apache"
>Apache variables</A
></H2
><P
> These variables are created by the <A
HREF="http://www.apache.org/"
TARGET="_top"
>Apache</A
> webserver. If you are running
another webserver, there is no guarantee that it will provide the
same variables; it may omit some, or provide others not listed
here. That said, a large number of these variables are accounted
for in the <A
HREF="http://hoohoo.ncsa.uiuc.edu/cgi/env.html"
TARGET="_top"
>CGI 1.1
specification</A
>, so you should be able to expect those.
</P
><P
> Note that few, if any, of these will be available (or indeed have
any meaning) if running PHP on the command line.
</P
><P
> <P
></P
><DL
><DT
>GATEWAY_INTERFACE</DT
><DD
><P
> What revision of the CGI specification the server is using;
i.e. 'CGI/1.1'.
</P
></DD
><DT
>SERVER_NAME</DT
><DD
><P
> The name of the server host under which the current script is
executing. If the script is running on a virtual host, this
will be the value defined for that virtual host.
</P
></DD
><DT
>SERVER_SOFTWARE</DT
><DD
><P
> Server identification string, given in the headers when
responding to requests.
</P
></DD
><DT
>SERVER_PROTOCOL</DT
><DD
><P
> Name and revision of the information protocol via which the
page was requested; i.e. 'HTTP/1.0';
</P
></DD
><DT
>REQUEST_METHOD</DT
><DD
><P
> Which request method was used to access the page; i.e. 'GET',
'HEAD', 'POST', 'PUT'.
</P
></DD
><DT
>QUERY_STRING</DT
><DD
><P
> The query string, if any, via which the page was accessed.
</P
></DD
><DT
>DOCUMENT_ROOT</DT
><DD
><P
> The document root directory under which the current script is
executing, as defined in the server's configuration file.
</P
></DD
><DT
>HTTP_ACCEPT</DT
><DD
><P
> Contents of the <TT
CLASS="literal"
>Accept:</TT
> header from the
current request, if there is one.
</P
></DD
><DT
>HTTP_ACCEPT_CHARSET</DT
><DD
><P
> Contents of the <TT
CLASS="literal"
>Accept-Charset:</TT
> header
from the current request, if there is one. Example:
'iso-8859-1,*,utf-8'.
</P
></DD
><DT
>HTTP_ENCODING</DT
><DD
><P
> Contents of the <TT
CLASS="literal"
>Accept-Encoding:</TT
> header
from the current request, if there is one. Example: 'gzip'.
</P
></DD
><DT
>HTTP_ACCEPT_LANGUAGE</DT
><DD
><P
> Contents of the <TT
CLASS="literal"
>Accept-Language:</TT
> header
from the current request, if there is one. Example: 'en'.
</P
></DD
><DT
>HTTP_CONNECTION</DT
><DD
><P
> Contents of the <TT
CLASS="literal"
>Connection:</TT
> header from
the current request, if there is one. Example: 'Keep-Alive'.
</P
></DD
><DT
>HTTP_HOST</DT
><DD
><P
> Contents of the <TT
CLASS="literal"
>Host:</TT
> header from the
current request, if there is one.
</P
></DD
><DT
>HTTP_REFERER</DT
><DD
><P
> The address of the page (if any) which referred the browser
to the current page. This is set by the user's browser; not
all browsers will set this.
</P
></DD
><DT
>HTTP_USER_AGENT</DT
><DD
><P
> Contents of the <TT
CLASS="literal"
>User_Agent:</TT
> header from
the current request, if there is one. This is a string
denoting the browser software being used to view the current
page; i.e. <TT
CLASS="computeroutput"
>Mozilla/4.5 [en] (X11; U; Linux
2.2.9 i586)</TT
>. Among other things, you can use
this value with <A
HREF="function.get-browser.html"
><B
CLASS="function"
>get_browser()</B
></A
> to tailor
your page's functionality to the capabilities of the user's
browser.
</P
></DD
><DT
>REMOTE_ADDR</DT
><DD
><P
> The IP address from which the user is viewing the current
page.
</P
></DD
><DT
>REMOTE_PORT</DT
><DD
><P
> The port being used on the user's machine to communicate with
the web server.
</P
></DD
><DT
>SCRIPT_FILENAME</DT
><DD
><P
> The absolute pathname of the currently executing script.
</P
></DD
><DT
>SERVER_ADMIN</DT
><DD
><P
> The value given to the SERVER_ADMIN (for Apache) directive in
the web server configuration file. If the script is running
on a virtual host, this will be the value defined for that
virtual host.
</P
></DD
><DT
>SERVER_PORT</DT
><DD
><P
> The port on the server machine being used by the web server
for communication. For default setups, this will be '80';
using SSL, for instance, will change this to whatever your
defined secure HTTP port is.
</P
></DD
><DT
>SERVER_SIGNATURE</DT
><DD
><P
> String containing the server version and virtual host name
which are added to server-generated pages, if enabled.
</P
></DD
><DT
>PATH_TRANSLATED</DT
><DD
><P
> Filesystem- (not document root-) based path to the current
script, after the server has done any virtual-to-real
mapping.
</P
></DD
><DT
>SCRIPT_NAME</DT
><DD
><P
> Contains the current script's path. This is useful for pages
which need to point to themselves.
</P
></DD
><DT
>REQUEST_URI</DT
><DD
><P
> The URI which was given in order to access this page; for
instance, '/index.html'.
</P
></DD
></DL
>
</P
></DIV
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="language.variables.predefined.environment"
>Environment variables</A
></H2
><P
> These variables are imported into PHP's global namespace from the
environment under which the PHP parser is running. Many are
provided by the shell under which PHP is running and different
systems are likely running different kinds of shells, a
definitive list is impossible. Please see your shell's
documentation for a list of defined environment variables.
</P
><P
> Other environment variables include the CGI variables, placed
there regardless of whether PHP is running as a server module or
CGI processor.
</P
></DIV
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="language.variables.predefined.php"
>PHP variables</A
></H2
><P
> These variables are created by PHP itself.
</P
><P
> <P
></P
><DL
><DT
>argv</DT
><DD
><P
> Array of arguments passed to the script. When the script is
run on the command line, this gives C-style access to the
command line parameters. When called via the GET method, this
will contain the query string.
</P
></DD
><DT
>argc</DT
><DD
><P
> Contains the number of command line parameters passed to the
script (if run on the command line).
</P
></DD
><DT
>PHP_SELF</DT
><DD
><P
> The filename of the currently executing script, relative to
the document root. If PHP is running as a command-line
processor, this variable is not available.
</P
></DD
><DT
>HTTP_COOKIE_VARS</DT
><DD
><P
> An associative array of variables passed to the current
script via HTTP cookies. Only available if variable tracking
has been turned on via either the <A
HREF="configuration.html#ini.track-vars"
>track_vars</A
> configuration
directive or the
<TT
CLASS="computeroutput"
><?php_track_vars?></TT
>
directive.
</P
></DD
><DT
>HTTP_GET_VARS</DT
><DD
><P
> An associative array of variables passed to the current
script via the HTTP GET method. Only available if variable
tracking has been turned on via either the <A
HREF="configuration.html#ini.track-vars"
>track_vars</A
> configuration
directive or the
<TT
CLASS="computeroutput"
><?php_track_vars?></TT
>
directive.
</P
></DD
><DT
>HTTP_POST_VARS</DT
><DD
><P
> An associative array of variables passed to the current
script via the HTTP POST method. Only available if variable
tracking has been turned on via either the <A
HREF="configuration.html#ini.track-vars"
>track_vars</A
> configuration
directive or the
<TT
CLASS="computeroutput"
><?php_track_vars?></TT
>
directive.
</P
></DD
></DL
>
</P
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