in reply to Net::SSH2 channel returns no output

I think your program is asking too early for output:

$session->blocking(0) ;

I think you will need to rework your program logic in a way that it handles results other than the "in" event in a loop. Or you could maybe switch to blocking processing since you will wait for answers from the remote end anyway.

Replies are listed 'Best First'.
Re^2: Net::SSH2 channel returns no output
by rama133101 (Novice) on Apr 25, 2015 at 20:44 UTC

    Thanks for the quick reply

    Here is the full logic.

    $session = Net::SSH2->new(); $rc = $session->connect($target_ip, $target_port, Timeout=>4000) ; $session->auth_password($username, $passwd) ; $chan = $session->channel(); $chan->shell() ; print $chan $cmd . " \n" ; my @poll = ({handle=>$chan, events=>['in', 'ext', 'channel_closed']}); my $job_done = 1; my $status; while ($job_done > 0) { $session->blocking(0) ; $session->poll(1, \@poll) ; if ($poll[0]->{revents}->{in}) { while (<$chan>) { $resp .= $_ ; } $status = 0 ; if ($chan->eof()) { $status = $chan->exit_status() ; } } if ($poll[0]->{revents}->{ext}) { my ($len, $buff) ; while ($len = $chan->read($buff, 1024, 1)) { $resp .= $buff ; } if (! $resp) { $status = $chan->exit_status() || 0 ; } } elsif ($poll[0]->{revents}->{channel_closed}) { while (<$chan>) { $resp .= $_ ; } $status = $chan->exit_status() ; } if ($chan->eof() || $poll[0]->{revents}->{ext} || ($poll[0]->{revents}->{channel_closed} && $status == 0)) { $chan->close ; $job_done = -1; } $session->blocking(1) ; } print "\nresponse : $resp";

    The problem here is, commands that take more than 5 seconds to respond returns null. Whereas, commands that takes less time to respond are returning the exact result

    This is where sleep comes into picture for me

    Please help.

      Using Net::SSH2 reliably is quite hard, specially in non-blocking mode. Also, there were several bugs and mismatches between the underlaying libssh2 and the Net::SSH2 wrapper that I have fixed on the development version, but they are still waiting for a new module release.

      You may like to try Net::SSH::Any with the Net::SSH2 backend instead. The latest stable version (0.04) was able to workaround most of the issues... well, at least it seemed to work most of the time. 0.04, come out before I went into Net::SSH2/libssh2 internals, I wrote it just looking at the docs, with lots of wrong assumptions!!!