Re: Telnet client

end
end

It simply get what user input and put it on the telnet server.

I am having to guess here, but I imagine that tn is an instance of a
Net::Telnet object?

You haven’t described exactly what your problem is. In what way do your
“failed operations” fail? What exactly do the users type, what do they
see
in response, and what do you expect them to see?

I can see a few problems with the above code though.

  • ‘gets’ receives a whole line at a time. If you try to use an
    interactive
    program like vi, it will fail. If that’s not what you want, have a
    look
    at Curses, HighLine, or ruby-termios.
    http://codeidol.com/other/rubyckbk/User-Interface/Getting-Input-One-Character-at-a-Time/

  • In the third line above, under ruby 1.8 the block parameter ‘c’ is
    bound
    to the same variable as the ‘c’ outside. This means that the value of
    ‘c’
    will have changed after the block has executed. This means that if c
    was equal to ‘exit’ before, it may not be equal afterwards if the
    block
    has been invoked one or more times.

  • c will never equal “exit” because you are reading whole lines with
    their
    terminator. It will be “exit\n”.

So a cleaned-up version of your code might be:

loop do
c = gets
tn.cmd© { |resp| print resp }
break if c == “exit\n”
end

Having said that, it would be better to detect if the far end drops the
connection rather than seeing if the user typed “exit”. The user could
legitimately type “exit” for reasons other than logging out; and they
could
logout by typing “logout”.

I’m not sure the best way to do that with Net::Telnet. If you’re waiting
for
a specific response then you can test whether the value returned from
‘cmd’
matches the string you were expecting. Otherwise, you can try sending
data
and rescuing the Errno::EPIPE you get if the other end has closed.

I’d say that Net::Telnet is really designed for scripting telnet
sessions,
not for writing your own interactive telnet client.

HTH,

Brian.

c = gets

One more point: that should say “c = STDIN.gets” for an interactive
program.

“c = gets” will work until you try to pass arguments on the command line
(using ARGV). That’s because the bare ‘gets’ will treat those arguments
as
the names of files to read.

Regards,

Brian.

Can anybody help me on this? Is there a problem with “gets”? I changed
it to “STDIN.gets” but still have such problem.

Hmm, I think someone said the gateway to ruby-forum was broken - is that
still true?

My responses to this one are visible at
http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/314220
http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/314221

but not at
http://www.ruby-forum.com/topic/165048

Regards,

Brian.

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