I am troublesdhooting a perl expect script that interacts with a remote server running a custom OS on top of an OpenBSD kernel. The script creates an ssh connection and logs in successfully. It even shows the welcoming text of the custom OS and matches on the first custom OS's prompt. The script then sends a command to the remote server and the perl expect script echos back the command and closes the connection. I found the bit of trouble code in the Expect.pm module on or around lin 821 my $nread = sysread($exp, $buffer, 2048);. This sysread call fails to read anything off the socket after the system command is sent to the remote server and then sets $nread to 0 which is later interpreted into an EOF and sent to the server, $nread = 0 unless defined ($nread);. 
if ($nread == 0) {
   ...
   ...
   blah
   blah
   $exp->hard_close();
}

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First I thought it may be an issue with the tty or pty type because the app I am interacting with is not a standard type terminal service (popular Linux/BSD OS, cisco router, ssh console, etc). I tried setting the session to raw but that didn't help either. I then found some code in Expect.pm that appears to be re-assigning STDIN, STDOUT and STDERR starting on or around line 158: 
    close(STDIN);
    open(STDIN,"<&". $slv->fileno())
      or die "Couldn't reopen STDIN for reading, $!\n";
    close(STDOUT);
    open(STDOUT,">&". $slv->fileno())
      or die "Couldn't reopen STDOUT for writing, $!\n";
    close(STDERR);
    open(STDERR,">&". $slv->fileno())
      or die "Couldn't reopen STDERR for writing, $!\n";

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Could this have anything to do with it? Anyone suggestions on how I can get this to work with my non-standard OS?

In reply to Expect.pm early termination? by Elijah

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