old_contents: var express = require('express');
  
  var app = express();
  
  var http = require('http').Server(app);
  var io = require('socket.io')(http);
  var fs = require('fs');
  var path = require('path');
  
  var spawn = require('child_process').spawn;
  var proc;
  
  app.use('/', express.static(path.join(__dirname, 'public')));
  
  app.get('/', function(req, res) {
      res.sendFile(__dirname + '/public/index.html');
  });
  
  var sockets = {};
  
  io.on('connection', function (socket) {
      sockets[socket.id] = socket;
      console.log("Total clients connected : ", Object.keys(sockets).length);
  
      socket.on('disconnect', function() {
          delete sockets[socket.id];
  
          // no more sockets, kill the stream
          if (Object.keys(sockets).length == 0) {
              app.set('watchingFile', false);
              if (proc) proc.kill();
              fs.unwatchFile(__dirname + '/public/stream/image_stream.jpg');
          }
      });
  
      socket.on('start-stream', function() {
          startStreaming(io);
      });
  });
  
  http.listen(3000, function() {
      console.log('listening on *:3000');
  });
  
  function stopStreaming() {
      if (Object.keys(sockets).length == 0) {
          app.set('watchingFile', false);
          if (proc) proc.kill();
          fs.unwatchFile(__dirname + '/public/stream/image_stream.jpg');
      }
  }
  
  function startStreaming(io) {
      if (app.get('watchingFile')) {
          io.sockets.emit('liveStream', 'image_stream.jpg?_t=' + (Math.random() * 100000));
          return;
      }
  
      var args = ["-w", "640", "-h", "480", "-o", "./stream/image_stream.jpg", "-t", "999999999", "-tl", "100"];
      proc = spawn('raspistill', args);
  
      console.log('Watching for changes...');
  
      app.set('watchingFile', true);
  
      fs.watchFile(__dirname + '/public/stream/image_stream.jpg', function(current, previous) {
          io.sockets.emit('liveStream', 'image_stream.jpg?_t=' + (Math.random() * 100000));
      });
  }
  
new_contents: var express = require('express');
  
  var app = express();
  
  var http = require('http').Server(app);
  var io = require('socket.io')(http);
  var fs = require('fs');
  var path = require('path');
  
  var spawn = require('child_process').spawn;
  var proc;
  
  app.use('/', express.static(path.join(__dirname, 'public')));
  
  app.get('/', function(req, res) {
      res.sendFile(__dirname + '/public/index.html');
  });
  
  var sockets = {};
  
  io.on('connection', function (socket) {
      sockets[socket.id] = socket;
      console.log("Total clients connected : ", Object.keys(sockets).length);
  
      socket.on('disconnect', function() {
          delete sockets[socket.id];
  
          // no more sockets, kill the stream
          if (Object.keys(sockets).length == 0) {
              app.set('watchingFile', false);
              if (proc) proc.kill();
              fs.unwatchFile(__dirname + '/public/stream/image_stream.jpg');
          }
      });
  
      socket.on('start-stream', function() {
          startStreaming(io);
      });
  });
  
  http.listen(3000, function() {
      console.log('listening on *:3000');
  });
  
  function stopStreaming() {
      if (Object.keys(sockets).length == 0) {
          app.set('watchingFile', false);
          if (proc) proc.kill();
          fs.unwatchFile(__dirname + '/public/stream/image_stream.jpg');
      }
  }
  
  function startStreaming(io) {
      if (app.get('watchingFile')) {
          io.sockets.emit('liveStream', 'image_stream.jpg?_t=' + (Math.random() * 100000));
          return;
      }
  
      var args = ["-w", "640", "-h", "480", "-o", __dirname + "/public/stream/image_stream.jpg", "-t", "999999999", "-tl", "100"];
      proc = spawn('raspistill', args);
  
      console.log('Watching for changes...');
  
      app.set('watchingFile', true);
  
      fs.watchFile(__dirname + '/public/stream/image_stream.jpg', function(current, previous) {
          io.sockets.emit('liveStream', 'image_stream.jpg?_t=' + (Math.random() * 100000));
      });
  }
  
subject: fix raspistill save path