I removed the line:(for which I just realized that I had forgot to change "show ip arp")

my ($pty,$pid) = $ssh->open2pty
      or die "unable to run remote command show ip arp";
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and the results were that the "channel 4: open failed: resource shortage:" error went away. As for the remaining error, I guess i'll just filter it out since it's probably harmless as you said.

I appreciate the tip on writing follow ups, I never realized that it could cause that. Now I have a much more solid solution compared to using the Net::SSH::Expect module. For those interested, I cleaned up my code:...

#!/usr/bin/perl

use strict;
use warnings;
use Net::OpenSSH;

my $host = '10.0.0.1';

my $ssh = Net::OpenSSH->new("$host", timeout => 30);
$ssh->error and die "unable to connect to remote host: ". $ssh->error;

my $output = $ssh->capture({stdin_data =>
        "term length 0\nterm width 512\nsh ver\nsh run\nexit\n"});
print $output;
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Thank you Salva