Expect is a program that performs programmed dialogue with other
interactive programs.  It is briefly described by its man page, expect(1).

It uses pseudo-tty's to control the child processes, so it is not affected
by programs that refuse to read from stdin or pipes. (eg: passwd(1) etc).

The Expect home page is: http://expect.nist.gov
The Expect FAQ is:       http://expect.nist.gov/FAQ.html