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 <html><head><title>CGI Script output</title></head><body><h1><img alt="" src="out_files/CGIlogo.gif"> CGI Script Output</h1>
 <hr>

 <h2>Script output</h2>

 The script sends its output to stdout. This output can either be a
 document generated by the script, or instructions to the server for
 retrieving the desired output. <p>
 </p><hr>

 <h2>Script naming conventions</h2>

 Normally, scripts produce output which is interpreted and sent back to
 the client. An advantage of this is that the scripts do not need to
 send a full HTTP/1.0 header for every request.  <p>
 <a name="nph">
 Some scripts may want to avoid the extra overhead of the server
 parsing their output, and talk directly to the client. In order to
 distinguish these scripts from the other scripts, CGI requires that
 the script name begins with nph- if a script does not want the server
 to parse its header. In this case, it is the script's responsibility
 to return a valid HTTP/1.0 (or HTTP/0.9) response to the client.  </a></p><p>

 </p><hr>
 <h2><a name="nph">Parsed headers</a></h2>

 <a name="nph">The output of scripts begins with a small header. This header consists
 of text lines, in the same format as an </a><a href="http://www.w3.org/hypertext/WWW/Protocols/HTTP/Object_Headers.html">
 HTTP header</a>, terminated by a blank line (a line with only a
 linefeed or CR/LF). <p>

 Any headers which are not server directives are sent directly back to
 the client. Currently, this specification defines three server
 directives:</p><p>

 </p><ul>
 <li> <code>Content-type</code> <p>

     This is the MIME type of the document you are returning.  </p><p>

 </p></li><li> <code>Location</code> <p>

     This is used to specify to the server that you are returning a
     reference to a document rather than an actual document. </p><p>

     If the argument to this is a URL, the server will issue a redirect
     to the client. </p><p>

     If the argument to this is a virtual path, the server will
     retrieve the document specified as if the client had requested
     that document originally. ? directives will work in here, but #
     directives must be redirected back to the client.</p><p>


 </p></li><li> <a name="status"><code>Status</code></a><p>

     This is used to give the server an HTTP/1.0 <a href="http://www.w3.org/hypertext/WWW/Protocols/HTTP/HTRESP.html">status
 line</a> to send to the client. The format is <code>nnn xxxxx</code>,
 where <code>nnn</code> is the 3-digit status code, and
 <code>xxxxx</code> is the reason string, such as "Forbidden".</p><p>

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

 <hr>
 <h2>Examples</h2>

 Let's say I have a fromgratz to HTML converter. When my converter is
 finished with its work, it will output the following on stdout (note
 that the lines beginning and ending with --- are just for illustration
 and would not be output): <p>

 </p><pre>--- start of output ---
 Content-type: text/html

 --- end of output ---
 </pre>

 Note the blank line after Content-type. <p>

 Now, let's say I have a script which, in certain instances, wants to
 return the document <code>/path/doc.txt</code> from this server just
 as if the user had actually requested
 <code>http://server:port/path/doc.txt</code> to begin with. In this
 case, the script would output: </p><p>
 </p><pre>--- start of output ---
 Location: /path/doc.txt

 --- end of output ---
 </pre>

 The server would then perform the request and send it to the client.
 <p>

 Let's say that I have a script which wants to reference our gopher
 server. In this case, if the script wanted to refer the user to
 <code>gopher://gopher.ncsa.uiuc.edu/</code>, it would output: </p><p>

 </p><pre>--- start of output ---
 Location: gopher://gopher.ncsa.uiuc.edu/

 --- end of output ---
 </pre>

 Finally, I have a script which wants to talk to the client directly.
 In this case, if the script is referenced with <a href="http://hoohoo.ncsa.uiuc.edu/cgi/env.html#protocol"><code>SERVER_PROTOCOL</code></a> of HTTP/1.0,
 the script would output the following HTTP/1.0 response: <p>

 </p><pre>--- start of output ---
 HTTP/1.0 200 OK
 Server: NCSA/1.0a6
 Content-type: text/plain

 This is a plaintext document generated on the fly just for you.

 --- end of output ---
 </pre>


 <hr>

 <a href="http://hoohoo.ncsa.uiuc.edu/cgi/interface.html"><img alt="[Back]" src="out_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 Script output</title></head><body><h1><img alt="" src="out_files/CGIlogo.gif"> CGI Script Output</h1>
	<hr>

	<h2>Script output</h2>

	The script sends its output to stdout. This output can either be a
	document generated by the script, or instructions to the server for
	retrieving the desired output. <p>
	</p><hr>

	<h2>Script naming conventions</h2>

	Normally, scripts produce output which is interpreted and sent back to
	the client. An advantage of this is that the scripts do not need to
	send a full HTTP/1.0 header for every request. <p>
	<a name="nph">
	Some scripts may want to avoid the extra overhead of the server
	parsing their output, and talk directly to the client. In order to
	distinguish these scripts from the other scripts, CGI requires that
	the script name begins with nph- if a script does not want the server
	to parse its header. In this case, it is the script's responsibility
	to return a valid HTTP/1.0 (or HTTP/0.9) response to the client. </a></p><p>

	</p><hr>
	<h2><a name="nph">Parsed headers</a></h2>

	<a name="nph">The output of scripts begins with a small header. This header consists
	of text lines, in the same format as an </a><a href="http://www.w3.org/hypertext/WWW/Protocols/HTTP/Object_Headers.html">
	HTTP header</a>, terminated by a blank line (a line with only a
	linefeed or CR/LF). <p>

	Any headers which are not server directives are sent directly back to
	the client. Currently, this specification defines three server
	directives:</p><p>

	</p><ul>
	<li> <code>Content-type</code> <p>

	This is the MIME type of the document you are returning. </p><p>

	</p></li><li> <code>Location</code> <p>

	This is used to specify to the server that you are returning a
	reference to a document rather than an actual document. </p><p>

	If the argument to this is a URL, the server will issue a redirect
	to the client. </p><p>

	If the argument to this is a virtual path, the server will
	retrieve the document specified as if the client had requested
	that document originally. ? directives will work in here, but #
	directives must be redirected back to the client.</p><p>


	</p></li><li> <a name="status"><code>Status</code></a><p>

	This is used to give the server an HTTP/1.0 <a href="http://www.w3.org/hypertext/WWW/Protocols/HTTP/HTRESP.html">status
	line</a> to send to the client. The format is <code>nnn xxxxx</code>,
	where <code>nnn</code> is the 3-digit status code, and
	<code>xxxxx</code> is the reason string, such as "Forbidden".</p><p>

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

	<hr>
	<h2>Examples</h2>

	Let's say I have a fromgratz to HTML converter. When my converter is
	finished with its work, it will output the following on stdout (note
	that the lines beginning and ending with --- are just for illustration
	and would not be output): <p>

	</p><pre>--- start of output ---
	Content-type: text/html

	--- end of output ---
	</pre>

	Note the blank line after Content-type. <p>

	Now, let's say I have a script which, in certain instances, wants to
	return the document <code>/path/doc.txt</code> from this server just
	as if the user had actually requested
	<code>http://server:port/path/doc.txt</code> to begin with. In this
	case, the script would output: </p><p>
	</p><pre>--- start of output ---
	Location: /path/doc.txt

	--- end of output ---
	</pre>

	The server would then perform the request and send it to the client.
	<p>

	Let's say that I have a script which wants to reference our gopher
	server. In this case, if the script wanted to refer the user to
	<code>gopher://gopher.ncsa.uiuc.edu/</code>, it would output: </p><p>

	</p><pre>--- start of output ---
	Location: gopher://gopher.ncsa.uiuc.edu/

	--- end of output ---
	</pre>

	Finally, I have a script which wants to talk to the client directly.
	In this case, if the script is referenced with <a href="http://hoohoo.ncsa.uiuc.edu/cgi/env.html#protocol"><code>SERVER_PROTOCOL</code></a> of HTTP/1.0,
	the script would output the following HTTP/1.0 response: <p>

	</p><pre>--- start of output ---
	HTTP/1.0 200 OK
	Server: NCSA/1.0a6
	Content-type: text/plain

	This is a plaintext document generated on the fly just for you.

	--- end of output ---
	</pre>


	<hr>

	<a href="http://hoohoo.ncsa.uiuc.edu/cgi/interface.html"><img alt="[Back]" src="out_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>