example gulpfile for jekyll and sass

gulpfile.js

var gulp        = require('gulp');
var gutil       = require('gulp-util');
var sass        = require('gulp-ruby-sass') ;
var prefix      = require('gulp-autoprefixer');
var uglify      = require('gulp-uglify');
var concat      = require('gulp-concat');
var filter      = require('gulp-filter');
var sourcemaps  = require('gulp-sourcemaps');
var minifycss   = require('gulp-minify-css');
var browserSync = require('browser-sync');
var cp          = require('child_process');
var exec        = cp.exec;
var os          = require('os');
var ifaces      = os.networkInterfaces();

// Check if running on windows, if we are use jekyll.bat as child_process, if its not just use jekyll]
// more info: http://stackoverflow.com/q/21856861/
var jekyll = process.platform === "win32" ? "jekyll.bat" : "jekyll";

// THIS FUNCTION GETS YOUR LOCAL IP SO WE CAN SERVE THE BUILT SITE FROM IT
// No more having to keep swapping the IP
var lookupIpAddress = null;
for (var dev in ifaces) {
    if(dev != "en1" && dev != "en0") {
        continue;
    }
    ifaces[dev].forEach(function(details){
        if (details.family=='IPv4') {
            lookupIpAddress = details.address;
        }
    });
};
var ipAddress   = lookupIpAddress;

// The browser sync task
// info here http://www.browsersync.io/docs/gulp/
gulp.task('browser-sync', ['sass', 'jekyll-build'], function() {
    browserSync.init({
    		// available options here: http://www.browsersync.io/docs/options/
        server: {
            baseDir: './build'
        },
        // uses the ipaddress variable we made up top
        host: ipAddress,
        // A delay between changes and reloading so 2 changes in quick succession don't get missed
        reloadDelay: 2000,
        // all off by default, but enables multiple browsers to all browse in sync
        ghostMode: {
            clicks: false,
            links: false,
            forms: false,
            scroll: false
        },
        // opens the browser when you run gulp
        open: true,
        // displays message in browser when reload happens or styles injected
        notify: true,
        // shows browsers connected in command line
        logConnections: true

    })
});

gulp.task('sass', function (){
	// source file 
   gulp.src('./dev/assets/sass/*.scss')
    .pipe(sass({
        sourcemap: true,
        sourcemapPath: '../../',
        style: 'expanded',
        // show any errors in browser sync in browser notifications
        onError: browserSync.notify
    }))
    // where the files are built to
    .pipe(gulp.dest('./dev/assets/css'))
    // autoprefixer task http://git.io/FV2akw
    .pipe(prefix(
    		// modern browsers only as POC
    		// not suitable setting for production environments
        "last 1 version"
        ))
    .pipe(gulp.dest('./dev/assets/css'))
    // minify the css
    .pipe(minifycss())
    // remove and source map (css.map) files from the stream as they will cause full page reload : (
    .pipe(filter('**/*.css'))
    // final css 
    .pipe(gulp.dest('./build/assets/css'))
    // pipe the stream to the browsersync reload task to update the css without refreshing the page
    .pipe(browserSync.reload({stream:true}));
});

// Jekyll task - basically runs the command line command 'jekyll build' with node
gulp.task('jekyll-build', function (done) {
		// uses our jekyll variable we made earlier
    return cp.spawn(jekyll, ['build'], {stdio: 'inherit'})
        .on('close', done);
});

// runs the jekyll command above but reloads the browser when complete
gulp.task('jekyll-rebuild', ['jekyll-build'], function () {
    browserSync.reload();
});

// runs the jekyll command but using the staging options
gulp.task('jekyll-staging', function (){
    exec('jekyll build --config [_config.yml,_config.staging.yml]', function(err, stdout, stderr) {
        console.log(stdout);
    });
});

// watch the sass and html/js files for changes, then run the appropriate task
gulp.task('watch', function () {
    gulp.watch('./dev/assets/*/sass/**/*.scss', ['sass']);
    gulp.watch(['./dev/**/*.html', './dev/js/**/*.js'], ['jekyll-rebuild']);
});

// The default task run when you do 'gulp' on the command line
gulp.task('default', ['browser-sync', 'watch']);