Help using Expect.pm

gnangia has asked for the wisdom of the Perl Monks concerning the following question:

Hello fellow monks,
I am using the Expect module (v1.15) to automate a simple telnet process that logs in and sends a sample ping. Now I know I can probably use the Net::Telnet module, but I am using this for a purpose. Here is a snippet of my code (logtext is a simple function writing to a logfile).

while($perform_step > 0)
{
    if ($tcp_transx_param{$row_ref->[$i]}{$perform_step})
    {
        logtext "Value of step is $perform_step";
        logtext "Sending =>$tcp_transx_param{$row_ref->[$i]}{$perform_
+step}{send}<=";
        $session->send("$tcp_transx_param{$row_ref->[$i]}{$perform_ste
+p}{send}\r");
        $session->expect($expect_timeout, '-re', "$tcp_transx_param{$r
+ow_ref->[$i]}{$perform_step}{expect}") || warn "Did not match at step
+ $perform_step for CollectionID $row_ref->[$i]" . $session -> exp_err
+or();
        logtext "Expecting =>$tcp_transx_param{$row_ref->[$i]}{$perfor
+m_step}{expect}<=";
        if ($session->exp_error())
        {
            logtext "ERROR=>" . $session->exp_error();
            logtext "Closing Session";
            $session->hard_close();
            last;
        }
        else { $perform_step++; }
    }
    else
    {
        $perform_step=0;
        $session->soft_close();
        last;
    }
    logtext "Increasing my step to $perform_step";
}
[download]

The issue I seem to be having is that the while loop continues regardless of the response. It works fine with the correct password but if I use the wrong password, then it continues and reports failure at the wrong step. Please help.

Comment on Help using Expect.pm Download Code

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Re: Help using Expect.pm by gnangia (Scribe) on Dec 03, 2002 at 23:15 UTC
Did some troubleshooting and the problem seems to be when looking for the string "$", it is not there in the response, but the module log file says it is - spawn id(6): Does ` '^M match:^M pattern #1: -re `$'? YES!!^M Before match string: ` '^M Match string: `'^M After match string: `'^M Matchlist: ()^M Dec 03 18:09:57 Increasing my step to 5 Dec 03 18:09:57 Value of step is 5	[reply]
(bbfu) Re2: Help using Expect.pm by bbfu (Curate) on Dec 04, 2002 at 01:27 UTC
I'm pretty certain that the parameter to `expect()` is a regexp, which means that `$` would be the end-of-line marker, instead of a literal $. Try escaping it with a backslash. As an aside, it would help if you could include more of the surrounding code. Specifically where you set up the session, and the data that you're actually sending to the `send()` and `expect()` calls. It would be best if you reduced it to a "least-common-denominator" snippet that could be run and exhibits the problem. bbfu Black flowers blossum Fearless on my breath	[reply] [d/l] [select]
Re: (bbfu) Re2: Help using Expect.pm by gnangia (Scribe) on Dec 04, 2002 at 16:14 UTC
Thank-you...that was the problem. I had to escape the "$" character because it was interpreting it as the end-of-line marker in lieu of the literal $.	[reply]