Re: [SLUG] automating a Telnet session using EXPECT

[Angus Lees <gus@xxxxxxxxxxx>]

At Fri, 30 Aug 2002 17:46:24 +1000, Lucas King wrote:
> As i could not get satisfactory results from Expect i rewrote the entire 
> program in 'C'.  when i tested the code, exactly the same problems as i 
> had in Expect manifested themselves.  i kept getting control codes being 
> displayed to the screen.  after a certain period of time the Telnet 
> session reported that certain "variables" could not be set and then 
> continued on its merry way.
> 
> the control codes were not coming from the remote system.  these are 
> being passed through to the Telnet session OK.  the control codes are 
> being generated by the Telnet session on my local Linux box.  it is 
> trying to query the terminal type on the local system.  but as i had 
> redirected the Telnet input/output (using DUP2) to a pipe to another 
> process so that i could interact with the Telnet session via software, 
> the Telnet session was unable to obtain the values that it needed. 
>  Expect, i suspect, does exactly the same thing.  i conclude this only 
> because i am getting exactly the same "error" messages as it is.

try setting TERM=dumb or something before running the telnet
client. i'd hope that the relevant curses libraries wouldn't attempt
any fanciness with that sort of terminal..

otherwise, iirc expect creates a pty and does the whole terminal thing
itself (i've never actually used expect, so i could be completely
wrong here).  if the other end is expecting something cleverer than a
simple linear stream of bytes for output, then you may find yourself
having to mess with ptys yourself.

(i presume you're running the telnet client executable and messing
with stdin/stdout?  you could even dump that and just talk to the
network port yourself; the telnet protocol isn't too complicated if
you don't want any of the features.  of course, perl has a
Net::Telnet, which would make all of this easy ;)

-- 
 - Gus