ntail.js

#!/usr/bin/env node

var tcp = require("tcp");
var sys = require("sys"); 
var posix = require("posix"); 

var file = process.ARGV[2].toString();

Array.prototype.remove = function(e) {
  for(var i = 0; i < this.length; i++)
    if(e == this[i]) this.splice(i, 1);
}

Array.prototype.each = function(fn) {
  for(var i = 0; i < this.length; i++) fn(this[i]);
}

function Client(connection) {
  this.name = null;
  this.connection = connection;
}

var clients = [];

var server = tcp.createServer(function (socket) {
  var client = new Client(socket);
  clients.push(client);

  socket.setTimeout(0);
  socket.setEncoding("utf8");

  socket.addListener("close", function() {
    clients.remove(client);
    sys.puts("Closed connection from " + client.connection.remoteAddress);
  });
  
  socket.addListener("connect", function() {
    sys.puts("Received connection from " + client.connection.remoteAddress);
  })

  process.watchFile(file, function(current, previous) { 
    posix.open(file, process.O_RDONLY, 438).addCallback(function(fd) {    
      if (fd) {
        var size = current.size - previous.size;
        posix.read(fd, size, previous.size, "utf8").addCallback(function(data, bytes_read) {
          if (bytes_read > 0) {
            clients.each(function(client) {
              client.connection.send(data);
            });        
          }
        });
        posix.close(fd);
      }
    });
  });
});

server.listen(7000);
sys.puts("tail -f'ing " + file + " on port 7000")