NodeJs Log

append.js

fs.appendFile('message.txt', 'data to append', function (err) {
  if (err) throw err;
  console.log('Saved!');
});

read.js

var readline = require('readline');
var fs = require('fs');

var myInterface = readline.createInterface({
  input: fs.createReadStream('demofile1.html')
});

var lineno = 0;
myInterface.on('line', function (line) {
  lineno++;
  console.log('Line number ' + lineno + ': ' + line);
});