Nich240 has asked for the wisdom of the Perl Monks concerning the following question:

I am using Net::SSH2 to ssh into a NAS box, and run a command. I can get the command results while I am inside the loop. When I am outside the loop, I don't see the variable if it contains the output. However, I can see the variable if a new value is defined.

In the code below, I assign $result to $_. If I am inside the loop, I can see it. If I am outside the loop I cannot. However, I can define $result="test" before I leave the loop, and I can then see it outside the loop. It appears that I cannot pass the $_ (output of the NAS Command)

How do I pass the $_ outside the loop?

Here is my code: 
#!C:\strawberry\perl\bin
use warnings;
use strict;
use Net::SSH2;
use MIME::Lite;
use Config::Tiny;

my $ssh2 = Net::SSH2->new();
my $ipaddr="w.x.y.z";
my $username="username";
my $password="password";

        $ssh2->connect("$ipaddr") || die "PROBELM - $!";
        
        $ssh2->auth_password("$username","$password") || die "Username
+/Password not right";
        my $chan = $ssh2->channel();
         $chan->blocking(0);
        $chan->exec('export NAS_DB=/nas;/nas/bin/nas_fs -list');
        print "Chan= $chan\n";

my $result;

        while (<$chan>)
{
$result=$_; #Desired output.  Only works inside the loop.
$result='test'; #Used for testing, this works inside and outside of lo
+op
#print $result; #Works
}

print $result; #Works if $result is set, but not with a $_;
print "END";

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Re: Using Variable outside of loop with Net::SSH
by aaron_baugher (Curate) on May 08, 2015 at 13:30 UTC

    You can't get at the loop's inner value of $_ outside the loop, because the while command automatically localizes it. Just do it the way you do here with $result, by assigning it to a variable that does exist outside the loop.

    Aaron B.
    Available for small or large Perl jobs and *nix system administration; see my home node.

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      I understand that $_ is local. This is why I assign it to the $results variable. That variable is global. The strange part is that $result="test" will work outside the loop. To me, this would seem that since $result is initialized with "my" before the loop, I can use it inside out outside the loop. And, this works for almost all variables, $results="test" is good. So it seems to be correct. However, the problem is when I use $result=$_
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        Doing $result=$_ inside the loop should work, but after the loop, $result will have the value of $_ from the last loop that executed. That might not be what you expected. I would test it by trying something like this: 

        my $result;
while(<$chan>){
  $result = $_;
  print "Inside loop: $result\n";
}
print "Outside loop: $result\n";

        [download]

        That should show you what's being assigned in each loop, and the last inside loop should show the same value as what ends up outside it.

        One other thing: if you have other code inside the loop which you've removed for the sake of this sample, make sure it's not changing the value of $_ before you assign it to $result.

        Aaron B.
        Available for small or large Perl jobs and *nix system administration; see my home node.

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