gulp browserify + reactify not creating bundle - reactjs

Question

When I run gulp I get an "updating!" and "updated!" log after saving main.js but there's no bundle ever built
gulpfile.js:
var watchify = require('watchify');
var reactify = require('reactify');
var concat = require('gulp-concat');
var util = require('gulp-util');
gulp.task('browserify', function() {
var bundler = browserify({
entries: ['./dist/main.js'], // Only need initial file, browserify finds the deps
transform: [reactify], // We want to convert JSX to normal javascript
debug: true, // Gives us sourcemapping
cache: {}, packageCache: {}, fullPaths: true // Requirement of watchify
});
var watcher = watchify(bundler);
return watcher
.on('update', function () { // When any files update
var updateStart = Date.now();
console.log('Updating!');
watcher.bundle() // Create new bundle that uses the cache for high performance
.pipe(source('main.js'))
.on('error', util.log)
// This is where you add uglifying etc.
.pipe(gulp.dest('/build/'));
console.log('Updated!', (Date.now() - updateStart) + 'ms');
})
.on('error', util.log)
.bundle() // Create the initial bundle when starting the task
.pipe(source('main.js'))
.pipe(gulp.dest('/build/'))
.on('error', util.log);
});
// I added this so that you see how to run two watch tasks
gulp.task('css', function () {
gulp.watch('styles/**/*.css', function () {
return gulp.src('styles/**/*.css')
.pipe(concat('main.css'))
.pipe(gulp.dest('build/'));
});
});
// Just running the two tasks
gulp.task('default', ['browserify', 'css']);
My file structure is
/build
/dist
-index.html
-main.js
/node_modules
/styles
gulpfile.js
I am not finding any errors and I am completely lost at this point. I've tried changing directories around and reloading everything but nothing works.

Answer 1

Update lines that contain gulp.dest('/build/') to gulp.dest(__dirname + '/build/'). Currently your file located at drive_root_dir/build/main.js