Re: [Expectperl-discuss] expect closing port handle

[expect <ex...@ih...>]

On Mon, 04 Aug 2003 17:19:18 -0400
Sayre Swarztrauber <sa...@qu...> wrote:

> I am new to Expect. I am using it to control some serial devices that 
> our company manufactures. They are connected on /dev/tty ports directly 
> as RS232 devices. I open the port using IO::File and then connect that 
> handle to Expect.
> 
> I have a problem where Expect.pm occasionally closes the filehandle on 
> the port giving the following message from the debug output:
> 
> Waiting for new data (6 seconds)...
> handle id(3): new data.
> handle id(3): EOF
> handle id(3): closing...
> Returning from expect with TIMEOUT or EOF
> 
> 
> I have patched my problem by commenting out the       
> 
>  $exp->hard_close();
> 
> on line 853 of Expect.pm - which I realize is a drastic step.
> 
> What am I doing wrong? Why would expect decide to close my filehandle? 
> What can I do about it so that I do not have to modify the Expect.pm 
> program.
> 
> Any help would be greatly appreciated.


This sounds familiar to me...something about been there and done that.
Of course this may not be your problem.

I simply didn't understand that to cause Expect to wait forever on
a pattern match the perl 'undef' function has to be used in place of
a $timeout value.  What I did was just not define it and it didn't do
what I Expect'd.

my $proghandle = new Expect;
$proghandle = Expect->spawn($myprog);
$proghandle->expect(undef, $whatiamexpecting);


It may make sense to modify the docs slightly to point out that the
perl function undef should be specified.


perldoc Expect

"Simple interface:

 Given $timeout in seconds Expect will wait for $object's handle to
 produce one of the match_patterns. Due to o/s limitations $timeout
 should be a round number. If $timeout is 0 Expect will check one
 time to see if $object's handle contains any of the match_patterns.
 If $timeout is undef Expect will wait forever for a pattern to
 match."