Install

gem install jekyll bundler

Start your blog

jekyll serve --watch

to serve the drafts, add option --drafts.

There is another way to start the server:

bundle exec jekyll serve --watch --drafts

Build your blog

jekyll build JEKYLL_ENV=production

TIP: you can use ENV['JEKYLL_ENV'] to get/set the env instead of jekyll.environment variable

More at: Create static blog using github pages