gistfile1.txt

var fs = require('fs');

var buf = new Buffer(1024*1024);
buf.fill(42);

var fd = fs.openSync('file1', 'a+');
console.log("fd A: " + fd);

for (i = 0; i < 100; i++) {
  fs.write(fd, buf, 0, buf.length, i * buf.length, function(err) {
    if (err) console.log(err);
  });
}
  
fs.closeSync(fd);

var fd2 = fs.openSync('file2', 'a+');
console.log("fd B: " + fd2);