Looping through data provided by Net::SSH2 - perl

Question

I am using the following lib Net::SSH2
I can connect to my device and get the output OK in most case. Below is the relevant code:
sub logIntoDevice
{
my $self = shift;
my ($ssh2) = #_;
if(! $ssh2->connect($self->deviceIP))
{
say "Failed to connect to device:",$self->deviceIP;
$ssh2->disconnect();
exit 0;
}
if(! $ssh2->auth_password($self->usr, $self->pass))
{
say "Authentication Fail to ",$self->deviceIP;
$ssh2->disconnect();
exit 0;
}
my $channel = $ssh2->channel();
$channel->blocking(0);
$channel->shell();
return $channel;
}
sub sendCmd
{
my $self = shift;
my ($cmd,$channel) = #_;
my #cmdOutput;
print $channel "$cmd\n";
while (<$channel>)
{
chomp $_;
push(#cmdOutput, $_);
}
return #cmdOutput;
}
So below are the cmd i sent to the sub's. They work fine and the output is write to file OK.
$self->writeToFile($fileName,$self->sendCmd("show clock",$channel));
$self->writeToFile($fileName,$self->sendCmd("\n",$channel));
$self->writeToFile($fileName,$self->sendCmd("dir",$channel));
with the exception of when i sent the following cmd:
$self->writeToFile($fileName,$self->sendCmd("sh run",$channel));
the output of the cmd on the device using putty is:
sh run
Building configuration...
Current configuration : 16575 bytes
!
!
!Last configuration change at 16:37:19 CET+1 Sat Mar 15 2014
.....
but in the log file all you see is
sh run
Building configuration...
so the issue is the blank lines after the Building configuration output make the while (<$channel>) think its the end of the output.
My issue is I cant figure a way to loop through the data without using a While loop.
UPDATE
Ok come up with this solution but seems very clunky. must be a better way if doing this
sub sendCmd
{
my $self = shift;
my ($cmd,$channel) = #_;
my #cmdOutput;
my $currPrompt;
#get prompt. i am sure there is a better way!!! just cant figure it out
print $channel "\n";
while (<$channel>)
{
$currPrompt = $_;
}
print $channel "$cmd\n";
while(42)
{
my $inerOutput;
while (<$channel>)
{
chomp $_;
$inerOutput = $_;
push(#cmdOutput, $_);
}
if($inerOutput ne $currPrompt)
{
sleep(7);
}
else
{
last;
}
}
return #cmdOutput;
}

Answer 1

I don't think your issue is blank lines. Most likely, the issue is that you are using non-blocking mode, and it takes time for the device to perform the command. So you are getting an empty line (or an undef) after "Building configuration..." is read because there is no extra output produced yet.
I would use Net::SSH2's poll method with a timeout, which will let you know when there is something to read. If "sh run" takes substantially longer than other commands you are issuing, your sendCmd method needs to be aware of this, and allow more time to pass before it decides no more output is coming its way.
Alternatively, you can (as is the custom when using, for example, Net::Telnet) wait for more output until you see the prompt, whatever the prompt is for the device in question,
and then you will know that the command has finished its execution.

Answer 2

Net::SSH2->poll is deprecated as result of libss2_poll deprecation