my $cmd = '/opt/rssh/bin/ssh';

my $machine = "remote_machine";

open(my $fh, "-|", "$cmd $machine \"hostname;uptime\" 2>&1") or die "cannot open fh";

my $flags = fcntl($fh, F_GETFL, 0) or die "\ncan't get flags for the pipe: $!\n";
fcntl($fh, F_SETFL, $flags | O_NONBLOCK) or die "\ncan't set flags: $!\n";

my $out = $fh;
my $bytes_read = -1;
my $blocksize = 1024;
my $result = "";

while ($bytes_read) {
	my $buf;
	$bytes_read = sysread($out, $buf, $blocksize);
	if (defined($bytes_read)) {
		if ($bytes_read == 0) {
			close($out);
			last;
		} else {
			print "\nbuf content\n";
			$result.= $buf;
		} 
	}else {
		if ($! == EAGAIN()) {
			print "\nEAGAIN is set\n";
			last;
		} else {
			last;
		}
	}
}

print "\nresult is: $result \n";