use IO::Termios ();

my $handle = IO::Termios->open('/tmp/fakepty', '4800,8,n,1')
	or die  "IO::Termios->open: $!";
while (<$handle>) { # read the port line-by-line
	chomp;
	print time." <$_>\n";
	# write something to the port
	print {$handle} "Three!\n" if /3/;
}
close $handle;