Exploring Expect

Using Expect In Real Applications

Expect is a real program used in real applications. In my own environment, my colleagues depend on many Expect scripts to do important and critical tasks. We also use Expect to whip up demos and to automate ad hoc programs.

I have already mentioned lots of other uses for Expect. Many more cannot be described without also going into detail about proprietary or one-of-a-kind programs that people are stuck with using every day. But I will mention some companies and examples of how each uses Expect to give you a warm fuzzy feeling that Expect is widely accepted.

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. This is just a fraction of some of the users and uses of Expect. The whole list is truly astonishing, and it continues to grow rapidly.

In addition to this list of internal applications, companies such as IBM, AT&T, and Data General have incorporated Expect into applications that they sell. One of the best known commercial products utilizing Expect is DejaGnu, written by Rob Savoye for Cygnus Support. DejaGnu is a software testing utility designed to simplify the running of large collections of regression tests. Using Tcl and Expect, DejaGnu provides a framework in which tests can be written, run, and analyzed quickly and easily. Due to the power of Expect, DejaGnu is capable of testing both interactive and non-interactive applications, including embedded applications and applications on other hosts to support cross-platform and remote target board development. Cygnus has created freely available DejaGnu test suites for the GNU C and C++ compiler, debugger, assembler, and binary utilities. These test suites can be used to test any similar program or port of such a program, whether it is freely available or proprietary. According to the Free Software Report, Vol. 3, No. 1, “Cygnus supports over 70 platform configurations of the GNU compilers fully tested by DejaGnu. DejaGnu executes 8000 test cases in 16,000,000 documented tests for a typical release.”