Conceptual Overview

This tutorial aims to give the reader a taste of Expect and why it is worth your attention. The examples in this tutorial were written using Expect version 5.19 installed on my home directory (~dtly/usr/local/src/expect-5.19).

Introduction - What is Expect

Expect is a UNIX tool for automating interactive applications. In the past, testing interactive software often required a human to press keys and watch for correct responses. After a few iterations, this became quite tiresome. Naturally, people were much less likely to run thorough regression tests after making small changes that they thought probably didn't affect other parts of a program. Using Expect solves this problem. Expect reads a script that resembles the dialog itself and by following the script, Expect knows what can be expected from a program and what the correct responses should be. The script can specify responses by patterns, and can take different actions on different patterns.

Expect programs can be written in C or C++, but more than often are written in Tcl. Expect is integrated on top of Tcl and provides additional commands for interacting with programs. To learn what Tcl is, I suggest you go over the Tcl tutorial .

Note: Expect does not provide explicit support for character-based graphics.

Who uses Expect?

Here is short paragraph taken from the book, Exploring Expect, mentioning some companies and examples of how each uses Expect.

3Com does software quality assurance with Expect. Silicon Graphics uses it to do network measurements such as echo response time using telnet. The World Bank uses it to automate file transfers and updates. IBM uses it as part of a tape backup production environment. HP uses it to automate queries to multiple heterogenous commercial online databases. Sun uses it to sweep across their in-house network testing computer security. Martin Marietta uses it to control and extract usage statistics from network routers. Tektronix uses it to test software simulations of test instruments. The National Cancer Institute uses it to administer accounts across multiple platforms. Cisco uses it for network control and testing. Xerox uses it for researcher collaboration. Motorola uses it to control and backup multiple commercial databases. Data General uses it for software quality engineering. The Baha'i World Centre uses it to automate and coordinate data collection and storage from different telephone exchange locations. Amdahl uses it to automatically retrieve stock prices. CenterLine Software uses it for software quality assurance. Encore Computer uses it to simulate 500 users logging into one system at the same time. AT&T uses it to copy files between internal hosts through a firewall to and from external Internet hosts. Sandia National Laboratories uses it to control unreliable processes that need to be watched constantly. Schlumberger uses it to manage a network environment including routers, repeaters, bridges, and terminal servers all from different manufacturers. ComputerVision built an automated testbed using it.