tcp server code

server.js

var net = require('net');

var host = '0.0.0.0';
var port = 8000;
var readline = require('readline');
var os = require('os')
var EOL = os.EOL;
var cxn = net.createServer(function(sock) {

  sock.write('Ready for commands' + EOL);

  var socket = readline.createInterface({
    input: sock
  });

  socket.on('line', function(line){
    var cmd = line.substr(0, 4).toUpperCase();
    if (cmd == 'TIME') {
      var d = new Date();
      sock.write(d.toString() + EOL);
    }
    else if (cmd == 'ECHO') {
      sock.write(os.hostname() + EOL);
    }
    else if (cmd == 'EXIT') {
      sock.write('shutting down server' + EOL);
      sock.close();
    }
    else {
      sock.write("Unknown command: " + line + EOL);
    }
  });
}).listen(host, port, function(err){
  if(err){
    console.log(err);
  }
});