Without a timeout value, you can attempt to use the ssh connection before run_ssh() has finished what it's doing. This causes crazy stuff, like the script abending. In the op's example, testing the value of $login_output would not have necessarily solved anything. In the test script I wrote, it had no effect whatsoever (was always empty, whether the connection was successful or not). Additionally, adding the debug and log to stdout parms will help to track down what exactly is happening behind the run_ssh() call. If he waits until run_ssh() has finished, the regex check he included from the documentation will correctly determine whether he has a valid connection or not.

The doc for Net::SSH::Expect does imply $! as the location meaningful error information from run_ssh() with the statement:
$ssh->run_ssh() or die "SSH process couldn't start: $!";

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The fact that he "received nothing useful" from it leads me to believe he was checking trying to use the connection before run_ssh() had finished trying to connect.

In reply to Re^3: Problem with Net::SSH::Expect on unavailable hosts by jrsimmon
in thread Problem with Net::SSH::Expect on unavailable hosts by sierpinski

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