Guest Books

A guest books allows a visitor to your site to add a formatted comment to a list of comments in a web page that is in your site.

The guestbook CGI script is triggered by a form very much like the eform.cgi script that we covered in class. It uses the following magic variables:

FILE: a template file for the new entry, to format it and maybe add additional text, (which can include HTML tags)
HTMLFILE: This is the file that contains the guestbook. New entries are merged with this file.
EMAIL: an email address to send a notification to when a new entry is added.

Note that the names of these inputs must be in all uppercase, as shown.

Note also that the filenames must be complete absolute pathnames, so, for example:

<input type="hidden" name="FILE" value="/students/wwellesl/public_html/guestbook-entry.html">

The guestbook file needs to have a special comment in it that is exactly the following:

<!--- APPEND HERE --->

The comment has to be exactly that, because the CGI script looks for that exact bit of HTML and puts the new entry right there. If you add or remove a single hyphen, it won't work. Also, the comment must be exactly at the beginning of the line (don't indent even one space) in order to be found.

Finally, you have to make the guestbook file world-writable. You can do that using an FTP client. Using "Fetch," for example, select the guestbook file, then click on the "Get Info" icon (or "Remote / Get Info") and, then, under "Ownership and Permissions" check the "write" boxes for owner, group, and others. (The fine print says that the equivalent UNIX command is "666".)

The CGI script automatically puts the time of the entry at the beginning of the entry.

Here's an example:

This is the guestbook file. Feel free to add entries. That is, this is an example of the HTMLFILE file.
This is the guestbook entry file. This formats entries. That is, this is an example of the FILE file.
This is the form to add a new entry.

Note that in this example, I've separated the form for adding entries from the guestbook, but that's not required. There's no reason that the guestbook couldn't have the entry form at the top of it.

Written by Scott D. Anderson
scott.anderson@acm.org

This work is licensed under a Creative Commons License.