Re: [Ssh-sftp-perl-users] Problem getting output using Net::SSH2

[Steve P. <st...@fo...>]

Hmm, the sleep got it to work.

Does this mean that 'blocking' being set to 1 doesn't actually mean that 
the command executed by the shell blocks until it returns ? or is 
blocking set to 1 or 0 something else entirely ?

Which I guess means that the next question is 'how do you get it to wait 
until output returns' for a command that could return in an indefinite 
amount of time ? (without the obvious of lowest common denominator and 
getting all commands to wait for 20 seconds or so)

Also, thanks for the speedy response :-)

-- 
Steve.

On 5/05/2011 3:30 PM, Fitzpatrick, Robert M (Rob) wrote:
>
>   First, can you confirm that it is a simple timing issue, and not
> something about the input or output of your command?  What if you just
> run a "sleep 1", does that cause your issue?  Sleep 10?
>
> That will also give the rest of us a replicatable test situation if we
> can't resolve this quickly.
>
> Best of luck,
>    Rob
>
> -----Original Message-----
> From: Steve Phillips [mailto:st...@fo...]
> Sent: Wednesday, May 04, 2011 8:54 PM
> To: ssh...@li...
> Subject: [Ssh-sftp-perl-users] Problem getting output using Net::SSH2
>
> Hey There,
>
> I'm busy pulling my hair out over this one. I have a small script
> similar to the below.
>
> my $ssh2 = Net::SSH2->new();
> $ssh2->debug(1);
> $ssh2->connect($server) or die "Unable to connect Host $@ \n";
> $ssh2->auth_publickey($userName,$publicKey,$privateKey);
>
> my $chan = $ssh2->channel();
> $chan->blocking(0);
> $chan->shell();
>
> This seems to work quite happily and a connection is established,
> however - when running small commands (ls -l, whoami etc) everything
> works as expected
>
> print $chan "ls -la\n";
> while (<$chan>) { print "LINE: " . $_ }
>
> But, when I run a command that takes a while to return, I simply get a
> blank output.
>
> print $chan "vip/listmse /WideSpan/config/vipclient.conf 1 -c 'RADIUS
> Server'\n"; while (<$chan>) { print "LINE: " . $_ }
>
> The only thing I can think of is that the second command seems to take a
> few miliseconds longer to produce output.
>
> I've tried to play around with "$ssh2->poll(0)" which I read somewhere
> sets polling to infinite, but still no results.
>
> When debug is enabled I get thousands of lines similar to
>
> Net::SSH2::Channel::read(size = 1, ext = 0)
> - read 1 bytes
> - read 1 total
> Net::SSH2::poll: timeout = 250, array[1]
> - [0] = channel
> - [0] events 1
> - libssh2_poll returned 1
> - [0] revents 1
>
> scrolling up the screen, which I would assume means that I have exceeded
> a timeout of 250ms ?
>
> I've tried setting blocking to 0 and 1 with no joy either. (I've found
> that setting blocking to 0 when performing shell commands can lead to
> interesting output tho, so I assume that interactive shell commands
> should leave blocking to 1 ? setting to 0 seems to have interesting
> results when trying to run commands like ls -la)
>
> If I manually ssh into the remote box and run the command it returns
> values as expected, and if I do something similar using Net::SSH::Perl
> it works as well, however, Net::SSH::Perl seems to take upward of 30
> seconds to create a connection which isn't an option in this environment
> (and yeah - I've tried all the math module stuff which didn't seem to
> make a difference :-( )
>
> Any pointers as to why small/fast commands would work but commands that
> take around 1/2 a second to run would drop out would be appreciated.
>
> --
> Steve.
>