From: oinkoink+unet@... (Bret Jolly)
Date: 2004-05-18T08:08:49+09:00
Subject: PTY and expect tutorial and examples

Is there a tutorial or other simple documentation in English
on how to use PTY and expect?  I'm having a heck of a time
trying to figure them out.  I also cannot get the example
scripts to work.  For example, expect_sample.rb comes with
the ruby distribution (I'm using ruby 1.9.0 (2004-05-10) [i686-linux])
and supposedly uses ftp to ftp.ruby-lang.org to get the name
of the latest stable distribution.  Running this script tells
me that the distribution is "nil" and I can't get it to work
no matter how I hack it.  Even trying the simplest PTY program
I can think of:

require 'pty'
PTY.spawn("ls") { |r, w, pid|  puts r.readlines }

....leads to failure with the exception PTY::ChildExited.

The most infuriating thing is that, despite not knowing what
I am doing, I once had a Ruby expect script which invoked
a function in Pari/gp and took the string result back into
Ruby for further processing.  This script no longer works
correctly (it gives answers, but wrong answers).  I can't
figure out what is wrong because I don't understand PTY and
expect and I can't find functioning examples or useful 
documentation anywhere (the rdoc output is not useful documentation
here).  Any pointers to explanations and examples that actually
work will be greatly appreciated.  Thanks!

Regards, Bret