This is my gulpfile. There are many like it, but this one is mine.

gulpfile.js

var gulp = require('gulp'),
    plumber = require('gulp-plumber'),
    rename = require('gulp-rename');
var autoprefixer = require('gulp-autoprefixer');
var concat = require('gulp-concat');
var jshint = require('gulp-jshint');
var uglify = require('gulp-uglify');
var imagemin = require('gulp-imagemin'),
    cache = require('gulp-cache');
var minifycss = require('gulp-minify-css');
var less = require('gulp-less');
var browserSync = require('browser-sync');

gulp.task('browser-sync', function() {
    browserSync({
        proxy: 'example.dev'
    });
});

gulp.task('bs-reload', function () {
    browserSync.reload();
});

gulp.task('images', function(){
    gulp.src('assets/frontend/images/**/*.*')
        .pipe(cache(imagemin({ optimizationLevel: 3, progressive: true, interlaced: true })))
        .pipe(gulp.dest('public/img/'));
});

var jsFiles = [
    'bower_components/jquery/dist/jquery.js',
    // ----------------
    // bootstrap files
    // ----------------
    // 'bower_components/bootstrap/js/affix.js',
    //'bower_components/bootstrap/js/alert.js',
    //'bower_components/bootstrap/js/button.js',
    'bower_components/bootstrap/js/carousel.js',
    'bower_components/bootstrap/js/transition.js',
    'bower_components/bootstrap/js/collapse.js',
    'bower_components/bootstrap/js/dropdown.js',
//          'bower_components/bootstrap/js/modal.js',
    //'bower_components/bootstrap/js/popover.js',
//          'bower_components/bootstrap/js/scrollspy.js',
    'bower_components/bootstrap/js/tab.js',
    //'bower_components/bootstrap/js/tooltip.js',
    // lightbox image previews
    'bower_components/fancybox/source/jquery.fancybox.js',
    // jQuery form
    'bower_components/jquery-form/jquery.form.js',
    'bower_components/jquery-als/index.js',
    'bower_components/chained/jquery.chained.js'
];

gulp.task('styles', function(){
    gulp.src(['assets/frontend/less/app.less'])
        .pipe(plumber({
            errorHandler: function (error) {
                console.log(error.message);
                this.emit('end');
            }}))
        .pipe(less())

        // actually breaks bootstrap own compatibility mixins
        //.pipe(autoprefixer('last 2 versions'))

        .pipe(gulp.dest('public/frontend/css/'))
        //.pipe(rename({suffix: '.min'}))
        //.pipe(minifycss())
        //.pipe(gulp.dest('public/frontend/css/'))
        .pipe(browserSync.reload({stream:true}))
});

gulp.task('scripts', function(){
    var src = jsFiles;
    src.push('assets/frontend/js/**/*.js')
    return gulp.src(src)
        .pipe(plumber({
            errorHandler: function (error) {
                console.log(error.message);
                this.emit('end');
            }}))
        .pipe(jshint())
        .pipe(jshint.reporter('default'))
        .pipe(concat('app.js'))
        .pipe(gulp.dest('public/frontend/js/'))
        //.pipe(rename({suffix: '.min'}))
        //.pipe(uglify())
        //.pipe(gulp.dest('public/frontend/js/'))
        .pipe(browserSync.reload({stream:true}))
});

gulp.task('default', ['styles', 'scripts', 'browser-sync'], function(){
    gulp.watch("assets/frontend/less/**/*.less", ['styles']);
    gulp.watch("assets/frontend/js/**/*.js", ['scripts']);
    gulp.watch("assets/frontend/images/**/*.*", ['images']);
    gulp.watch("app/views/**/*.html.twig", ['bs-reload']);
});