Exploring Expect

Example—Automating Gopher and Mosaic telnet Connections

Gopher is an information system that follows links of information that may lead from one machine to another.^[57] The Gopher daemon does not support the ability to run interactive programs. For instance, suppose you offer public access to a service on your system, such as a library catalog. Since this is an interactive service, it is accessed by logging in, usually with a well-known account name such as "info“.

Put another way, for someone to use the service, they must telnet to your host and enter "info" when prompted for an account. You could automate this with an Expect script. Not so, under Gopher. The Gopher daemon is incapable of running interactive processes itself. Instead, the daemon passes the telnet information to the Gopher client. Then it is up to the Gopher client to run telnet and log in.

This means that the client system has to do something with the account information. By default, the Gopher client displays the information on the screen and asks the user to type it back in. This is rather silly. After all, the client knows the information yet insists on having the user enter it manually. It is not a matter of permission. The client literally tells the user what to type! Here is an example (with XXX to protect the guilty) from an actual Gopher session.

Figure 17-6. 

Even Mosaic, with its slick user interface, does ...