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 <html><head><title>CGI Environment Variables</title></head><body><h1><img alt="" src="env_files/CGIlogo.gif"> CGI Environment Variables</h1>
 <hr>

 <p>

 In order to pass data about the information request from the server to
 the script, the server uses command line arguments as well as
 environment variables. These environment variables are set when the
 server executes the gateway program. </p><p>

 </p><hr>
 <h2>Specification</h2>

  <p>
 The following environment variables are not request-specific and are
 set for all requests: </p><p>

 </p><ul>
 <li> <code>SERVER_SOFTWARE</code> <p>

     The name and version of the information server software answering
     the request (and running the gateway). Format: name/version </p><p>

 </p></li><li> <code>SERVER_NAME</code> <p>
     The server's hostname, DNS alias, or IP address as it would appear
     in self-referencing URLs. </p><p>

 </p></li><li> <code>GATEWAY_INTERFACE</code> <p>
     The revision of the CGI specification to which this server
     complies. Format: CGI/revision</p><p>

 </p></li></ul>

 <hr>

 The following environment variables are specific to the request being
 fulfilled by the gateway program: <p>

 </p><ul>
 <li> <a name="protocol"><code>SERVER_PROTOCOL</code></a> <p>
     The name and revision of the information protocol this request came
     in with. Format: protocol/revision </p><p>

 </p></li><li> <code>SERVER_PORT</code>  <p>
     The port number to which the request was sent. </p><p>

 </p></li><li> <code>REQUEST_METHOD</code> <p>
     The method with which the request was made. For HTTP, this is
     "GET", "HEAD", "POST", etc. </p><p>

 </p></li><li> <code>PATH_INFO</code> <p>
     The extra path information, as given by the client. In other
     words, scripts can be accessed by their virtual pathname, followed
     by extra information at the end of this path. The extra
     information is sent as PATH_INFO. This information should be
     decoded by the server if it comes from a URL before it is passed
     to the CGI script.</p><p>

 </p></li><li> <code>PATH_TRANSLATED</code> <p>
     The server provides a translated version of PATH_INFO, which takes
     the path and does any virtual-to-physical mapping to it. </p><p>

 </p></li><li> <code>SCRIPT_NAME</code> <p>
     A virtual path to the script being executed, used for
     self-referencing URLs. </p><p>

 </p></li><li> <a name="query"><code>QUERY_STRING</code></a> <p>
     The information which follows the ? in the <a href="http://www.ncsa.uiuc.edu/demoweb/url-primer.html">URL</a>
     which referenced this script. This is the query information. It
     should not be decoded in any fashion. This variable should always
     be set when there is query information, regardless of <a href="http://hoohoo.ncsa.uiuc.edu/cgi/cl.html">command line decoding</a>. </p><p>

 </p></li><li> <code>REMOTE_HOST</code> <p>
     The hostname making the request. If the server does not have this
     information, it should set REMOTE_ADDR and leave this unset.</p><p>

 </p></li><li> <code>REMOTE_ADDR</code> <p>
     The IP address of the remote host making the request. </p><p>

 </p></li><li> <code>AUTH_TYPE</code> <p>
     If the server supports user authentication, and the script is
     protects, this is the protocol-specific authentication method used
     to validate the user. </p><p>

 </p></li><li> <code>REMOTE_USER</code> <p>
     If the server supports user authentication, and the script is
     protected, this is the username they have authenticated as. </p><p>
 </p></li><li> <code>REMOTE_IDENT</code> <p>
     If the HTTP server supports RFC 931 identification, then this
     variable will be set to the remote user name retrieved from the
     server. Usage of this variable should be limited to logging only.
     </p><p>

 </p></li><li> <a name="ct"><code>CONTENT_TYPE</code></a> <p>
     For queries which have attached information, such as HTTP POST and
     PUT, this is the content type of the data. </p><p>

 </p></li><li> <a name="cl"><code>CONTENT_LENGTH</code></a> <p>
     The length of the said content as given by the client. </p><p>

 </p></li></ul>


 <a name="headers"><hr></a>

 In addition to these, the header lines received from the client, if
 any, are placed into the environment with the prefix HTTP_ followed by
 the header name. Any - characters in the header name are changed to _
 characters. The server may exclude any headers which it has already
 processed, such as Authorization, Content-type, and Content-length. If
 necessary, the server may choose to exclude any or all of these
 headers if including them would exceed any system environment
 limits. <p>

 An example of this is the HTTP_ACCEPT variable which was defined in
 CGI/1.0. Another example is the header User-Agent.</p><p>

 </p><ul>
 <li> <code>HTTP_ACCEPT</code> <p>
     The MIME types which the client will accept, as given by HTTP
     headers. Other protocols may need to get this information from
     elsewhere. Each item in this list should be separated by commas as
     per the HTTP spec. </p><p>

     Format: type/subtype, type/subtype </p><p>


 </p></li><li> <code>HTTP_USER_AGENT</code><p>

     The browser the client is using to send the request. General
 format: <code>software/version library/version</code>.</p><p>

 </p></li></ul>

 <hr>
 <h2>Examples</h2>

 Examples of the setting of environment variables are really much better
 <a href="http://hoohoo.ncsa.uiuc.edu/cgi/examples.html">demonstrated</a> than explained. <p>

 </p><hr>

 <a href="http://hoohoo.ncsa.uiuc.edu/cgi/interface.html"><img alt="[Back]" src="env_files/back.gif">Return to the
 interface specification</a> <p>

 CGI - Common Gateway Interface
 </p><address><a href="http://hoohoo.ncsa.uiuc.edu/cgi/mailtocgi.html">cgi@ncsa.uiuc.edu</a></address>

 </body></html>
	<html><head><title>CGI Environment Variables</title></head><body><h1><img alt="" src="env_files/CGIlogo.gif"> CGI Environment Variables</h1>
	<hr>

	<p>

	In order to pass data about the information request from the server to
	the script, the server uses command line arguments as well as
	environment variables. These environment variables are set when the
	server executes the gateway program. </p><p>

	</p><hr>
	<h2>Specification</h2>

	<p>
	The following environment variables are not request-specific and are
	set for all requests: </p><p>

	</p><ul>
	<li> <code>SERVER_SOFTWARE</code> <p>

	The name and version of the information server software answering
	the request (and running the gateway). Format: name/version </p><p>

	</p></li><li> <code>SERVER_NAME</code> <p>
	The server's hostname, DNS alias, or IP address as it would appear
	in self-referencing URLs. </p><p>

	</p></li><li> <code>GATEWAY_INTERFACE</code> <p>
	The revision of the CGI specification to which this server
	complies. Format: CGI/revision</p><p>

	</p></li></ul>

	<hr>

	The following environment variables are specific to the request being
	fulfilled by the gateway program: <p>

	</p><ul>
	<li> <a name="protocol"><code>SERVER_PROTOCOL</code></a> <p>
	The name and revision of the information protocol this request came
	in with. Format: protocol/revision </p><p>

	</p></li><li> <code>SERVER_PORT</code> <p>
	The port number to which the request was sent. </p><p>

	</p></li><li> <code>REQUEST_METHOD</code> <p>
	The method with which the request was made. For HTTP, this is
	"GET", "HEAD", "POST", etc. </p><p>

	</p></li><li> <code>PATH_INFO</code> <p>
	The extra path information, as given by the client. In other
	words, scripts can be accessed by their virtual pathname, followed
	by extra information at the end of this path. The extra
	information is sent as PATH_INFO. This information should be
	decoded by the server if it comes from a URL before it is passed
	to the CGI script.</p><p>

	</p></li><li> <code>PATH_TRANSLATED</code> <p>
	The server provides a translated version of PATH_INFO, which takes
	the path and does any virtual-to-physical mapping to it. </p><p>

	</p></li><li> <code>SCRIPT_NAME</code> <p>
	A virtual path to the script being executed, used for
	self-referencing URLs. </p><p>

	</p></li><li> <a name="query"><code>QUERY_STRING</code></a> <p>
	The information which follows the ? in the <a href="http://www.ncsa.uiuc.edu/demoweb/url-primer.html">URL</a>
	which referenced this script. This is the query information. It
	should not be decoded in any fashion. This variable should always
	be set when there is query information, regardless of <a href="http://hoohoo.ncsa.uiuc.edu/cgi/cl.html">command line decoding</a>. </p><p>

	</p></li><li> <code>REMOTE_HOST</code> <p>
	The hostname making the request. If the server does not have this
	information, it should set REMOTE_ADDR and leave this unset.</p><p>

	</p></li><li> <code>REMOTE_ADDR</code> <p>
	The IP address of the remote host making the request. </p><p>

	</p></li><li> <code>AUTH_TYPE</code> <p>
	If the server supports user authentication, and the script is
	protects, this is the protocol-specific authentication method used
	to validate the user. </p><p>

	</p></li><li> <code>REMOTE_USER</code> <p>
	If the server supports user authentication, and the script is
	protected, this is the username they have authenticated as. </p><p>
	</p></li><li> <code>REMOTE_IDENT</code> <p>
	If the HTTP server supports RFC 931 identification, then this
	variable will be set to the remote user name retrieved from the
	server. Usage of this variable should be limited to logging only.
	</p><p>

	</p></li><li> <a name="ct"><code>CONTENT_TYPE</code></a> <p>
	For queries which have attached information, such as HTTP POST and
	PUT, this is the content type of the data. </p><p>

	</p></li><li> <a name="cl"><code>CONTENT_LENGTH</code></a> <p>
	The length of the said content as given by the client. </p><p>

	</p></li></ul>


	<a name="headers"><hr></a>

	In addition to these, the header lines received from the client, if
	any, are placed into the environment with the prefix HTTP_ followed by
	the header name. Any - characters in the header name are changed to _
	characters. The server may exclude any headers which it has already
	processed, such as Authorization, Content-type, and Content-length. If
	necessary, the server may choose to exclude any or all of these
	headers if including them would exceed any system environment
	limits. <p>

	An example of this is the HTTP_ACCEPT variable which was defined in
	CGI/1.0. Another example is the header User-Agent.</p><p>

	</p><ul>
	<li> <code>HTTP_ACCEPT</code> <p>
	The MIME types which the client will accept, as given by HTTP
	headers. Other protocols may need to get this information from
	elsewhere. Each item in this list should be separated by commas as
	per the HTTP spec. </p><p>

	Format: type/subtype, type/subtype </p><p>


	</p></li><li> <code>HTTP_USER_AGENT</code><p>

	The browser the client is using to send the request. General
	format: <code>software/version library/version</code>.</p><p>

	</p></li></ul>

	<hr>
	<h2>Examples</h2>

	Examples of the setting of environment variables are really much better
	<a href="http://hoohoo.ncsa.uiuc.edu/cgi/examples.html">demonstrated</a> than explained. <p>

	</p><hr>

	<a href="http://hoohoo.ncsa.uiuc.edu/cgi/interface.html"><img alt="[Back]" src="env_files/back.gif">Return to the
	interface specification</a> <p>

	CGI - Common Gateway Interface
	</p><address><a href="http://hoohoo.ncsa.uiuc.edu/cgi/mailtocgi.html">cgi@ncsa.uiuc.edu</a></address>

	</body></html>