my $cmd = '/opt/rssh/bin/ssh';
my $machine = "remote_machine";

open(my $fh, "-|", "$cmd $machine \"hostname;sleep 5;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 = "";
my $buf;

$bytes_read = sysread($out, $buf, $blocksize);

print "\nl buf content is:\n $buf \n";
close $out;