#!/usr/bin/perl
use strict;
use warnings;
use Net::OpenSSH;

my $host = "127.0.0.1"; # remote IP
my $port = 22; # ssh default 22 change it
my $passwd = "username";
my $user = "password";

my %opts = ( passwd => $passwd, 
	     port   => $port, 
	     user   => $user );

my $ssh = Net::OpenSSH->new( $host , %opts );
$ssh->error and
    die "Couldn't establish SSH connection: ". $ssh->error;

my ($rout, $pid) = $ssh->pipe_out("vmstat") or
    die "pipe_out method failed: " . $ssh->error;

open my $write, ">", "test.txt" or die $!;

while (<$rout>) { print $write $_; }
close $rout;
close $write;

open my $read, "<", "test.txt" or die $!;

while (my $row = <$read>) {
  chomp $row;
  print "$row\n";
}

close $read;

__END__

Check also the test.txt file it contains the same output

procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 1  0  68716 390444   9520 674036    0    1    25    27  217  235  8  2 89  1  0