Re: [TCLUG:10172] Perl newbie - starting a telnet process...

[Clay Fandre <cfandre@maddog.mn-linux.org>]

I would recommend using expect. It is easier to use (in this particular
case) and is much nicer about timeouts and stuff like that. It also
comes with autoexpect, which automatically creates an expect script for
you. Very nice.

As far as your perl script goes, you are grabbing the output of the
telnet command instead of inputting to it. To input, the pipe goes after
the command:
open( TELNETPROC, "telnet|") || die "Unable to open telnet $!\n";

(do a perldoc -f open for more info)

open only allows for one way or the other. (Input or output.) That's why
I recommend expect. If you really need to use perl, look at open2, which
allows for 2-way communication to your process. (I'm not sure if it is
installed by default. Might have to install it from CPAN.)

Mike Glaser wrote:
> 
> I was trying to write a Perl script today that would telnet into a
> router, issue a few commands and then close. I wasn't having any
> luck. Can anyone tell me how to go about doing it?? Here are the
> particulars...
> 
> 1) telnet
> 2) open xxx.xxx.xxx.xxx
> 3) enter_password
> 4) command
> 5) exit
> 
> Here is what my script was looking like...
> 
> #!/usr/bin/perl
> open( TELNETPROC, "|telnet");
> print TELNETPROC "open 192.168.0.1\n";
> print TELNETPROC "thesecretpassword\n";
> print TELNETPROC "clear line 1\n";
> print TELNETPROC "exit\n";
> close FTPPROC;
> 
> What may I be missing here?? I have the O'Reilly book 'Learing Perl'
> to help me get started with Perl, but I have not been able to pick up
> much yet.
> 
> Thanks,
> Mike Glaser
> 
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-- 
Clay Fandre
cfandre@maddog.mn-linux.org
Twin Cities Linux Users Group
http://www.mn-linux.org