var tail = function(fname, onData, ender) {
    fs.open(fname, 'a+', function(err, fd) {
        if (err) {
            puts('tail error: '+err);
            if (ender(fd, 0) !== false) {
                setTimeout(function(){
                    tail(fname, onData);
                }, 10);
            }
        } else {
            puts('tailing');
            var size = 1024;
            var buffer = new Buffer(size);
            var pos = 0;
            var reader = function() {
                fs.read(fd, buffer, 0, size, null, function(err, bytesRead) {
                    if (bytesRead > 0) {
                        pos += bytesRead;
                        var outp = new Buffer(bytesRead);
                        buffer.copy(outp, 0, 0, bytesRead);
                        onData(outp, fd);
                    }
                    if (ender && ender(fd, pos) === false) {
                        fs.close(fd);
                    } else {
                        if (bytesRead == 0) {
                            setTimeout(reader, 10);
                        } else {
                            reader();
                        }
                    }
                });
            };
            reader();
        }
    });
};