expect uses Tcl as a language core. In addition, expect can use any UNIX program, whether or not it is interactive. The result is a classic example of a little language synergistically generating large power when combined with the rest of the UNIX workbench.
Previous papers have described the implementation of expect and compared it to other tools. This paper concentrates on the language, primarily by presenting a variety of scripts. Several scripts demonstrate brand-new features of expect.