Gulp file for Jekyll, with Sass, Autoprefixer, and browsersync

gulpfile.js

var gulp = require('gulp'),
    sass = require('gulp-ruby-sass'),
    autoprefixer = require('gulp-autoprefixer'),
    minifycss = require('gulp-minify-css'),
    jshint = require('gulp-jshint'),
    uglify = require('gulp-uglify'),
    rename = require('gulp-rename'),
    clean = require('gulp-clean'),
    concat = require('gulp-concat'),
    notify = require('gulp-notify'),
    cache = require('gulp-cache'),
    plumber = require('gulp-plumber'),
    browserSync = require('browser-sync'),
    cp = require('child_process');

gulp.task('styles', function() {
  return gulp.src('src/sass/*.sass')
    .pipe(plumber())
    .pipe(sass({ style: 'expanded' }))
    .pipe(autoprefixer('last 2 version', 'safari 5', 'ie 8', 'ie 9', 'opera 12.1', 'ios 6', 'android 4'))
    .pipe(gulp.dest('stylesheets'))
    .pipe(rename({suffix: '.min'}))
    .pipe(minifycss())
    .pipe(gulp.dest('stylesheets'))
    .pipe(gulp.dest('_site/stylesheets'))
    .pipe(browserSync.reload({stream:true}))
    .pipe(notify({ message: 'Styles task complete' }));
});

gulp.task('scripts', function() {
  return gulp.src('src/javascripts/**/*.js')
    //.pipe(jshint('.jshintrc'))
    //.pipe(jshint.reporter('default'))
    .pipe(concat('site.js'))
    .pipe(gulp.dest('javascripts'))
    .pipe(rename({suffix: '.min'}))
    .pipe(uglify())
    .pipe(gulp.dest('javascripts'))
    .pipe(gulp.dest('_site/javascripts'))
    .pipe(notify({ message: 'Scripts task complete' }));
});

gulp.task('clean', function() {
  return gulp.src(['stylesheets', 'javascripts'], {read: false})
    .pipe(clean());
});

/**
 * Build the Jekyll Site
 */
gulp.task('jekyll-build', function (done) {
    browserSync.notify('Building Jekyll');
    return cp.spawn('jekyll', ['build'], {stdio: 'inherit'})
        .on('close', done);
});

/**
 * Rebuild Jekyll & do page reload
 */
gulp.task('jekyll-rebuild', ['jekyll-build'], function () {
    browserSync.reload();
});

/**
 * Wait for jekyll-build, then launch the Server
 */
gulp.task('browser-sync', ['jekyll-build'], function() {
    browserSync.init(null, {
        server: {
            baseDir: '_site'
        },
        host: "localhost"
    });
});

gulp.task('watch', function() {
  // Watch .sass files
  gulp.watch('src/sass/**/*.sass', ['styles']);
  // Watch .js files
  gulp.watch('src/javascripts/**/*.js', ['scripts']);
  gulp.watch(['index.html', '_layouts/*.html', '_posts/*'], ['jekyll-rebuild']);
});

gulp.task('default', ['clean'], function() {
    gulp.start('styles', 'scripts', 'browser-sync', 'watch');
});

What about css-lint?

I am using this:

'use strict';
// import local config
var config = require('./Gulp.conf.js');

// lazy load plugins - $$.clean instead of requiring it
var $$ = require('gulp-load-plugins')();

// compiling css files
gulp.task('css', function () {
  return gulp.src(config.paths.css)
    .pipe($$.changed(config.dirs.min))
    .pipe($$.autoprefixer())
    .pipe($$.csslint(config.cssHint))
    .pipe($$.csslint.reporter())
    .pipe($$.minifyCss())
    .pipe(gulp.dest(config.dirs.min));
});

Note the changed plugin, so only changed or new files are compiled.

Then I am separately concatenating minimized files:

// concat minimized JS and CSS files
gulp.task('concat', function(){

  return [   {min: config.paths.min.js, concat: config.paths.concat.js}
    , {min: config.paths.min.css, concat: config.paths.concat.css} ].forEach(function (paths) {
      gulp.src(paths.min)
        //.pipe($$.watch())
        .pipe($$.concat(paths.concat))
        .pipe(gulp.dest(config.dirs.build));
  });

Thanks @dmitriz that's most helpful!