That works for my on a Windows XP virtual machine:

use IPC::Open2;

my ($read, $write);

my $pid = open2($read, $write, 'ssh -vv 10.0.2.3 -l salva');

syswrite $write, "ls && exit\n";

close $write;

while (1) {
    my $buf;
    sysread($read, $buf, 1) > 0 or last;
    print $buf;
}

close $read;

waitpid $pid, 0;
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Cygwin/OpenSSH do very scary things to simulate non-blocking pipes on Windows and sometimes they behave in unexpected ways!