iTP Secure WebServer System Administrator's Guide (Version 7.0)

Using Common Gateway Interface (CGI) Programs

iTP Secure WebServer System Administrator’s Guide—523346-012

8-26

Returning Output

The environment variable CONTENT_LENGTH specifies the number of bytes on

standard input.

For detailed information about processing forms input parameters, consult an

appropriate HTML resource.

Returning Output

Any output a CGI program writes to standard output is passed by the server to the

Web client. This output has three components:

•

One or more HTTP response headers

These headers contain descriptive information about the server response to a

request, such as the content (data) type, the number of bytes, and the expiration

time.

•

A blank line

This blank line is mandatory, even no content follows it. This requirement is

imposed by RFC 822; to see RFC 822, use the following URL:

http://www.faqs.org/rfcs/rfc822.html

•

The response content

The response content is the actual object being returned to a Web client. For

example, this content might consist of an HTML document, an image, or an audio

file.

A simple example of output from a CGI program:

Content-type: text/html

<TITLE>Example output</TITLE>

</HEAD><BODY>

This is the HTML document generated by a CGI program.

</BODY></HTML>

Response Headers

The headers used in all CGI responses take the form:

head_name: head_value

Table 8-5 on page 8-27 lists CGI response headers.