126 lines
4.4 KiB
HTML
126 lines
4.4 KiB
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> |