rm /tmp/foo && touch /tmp/foo

read-from-file.js

var fs = require("fs");

function read(fd) {
  var buf = new Buffer(8);
  fs.read(fd, buf, 0, buf.length, null, function () {
    console.log(buf);
    read(fd);
  });
}

fs.open("/tmp/foo", "r", function (err, fd) {
  read(fd);
});