遇到没有 /usr/bin 权限的问题：
sudo gem install -n /usr/local/bin bundler jekyll
# Build the site on the preview server bundle exec jekyll serve # preview drafts bundle exec jekyll serve --drafts
通过 http://localhost:4000 在本地测试
bundle show jekyll-theme-minimal
bundler is a gem that manages other Ruby gems. It makes sure your gems and gem versions are compatible, and that you have all necessary dependencies each gem requires.
The Gemfile and Gemfile.lock files inform Bundler about the gem requirements in your site.
You should prefix jekyll command with
bundle exec so that Bundler runs the version of Jekyll that is installed in your project folder.
The github-pages gem is what’s constraining you from update to latest Jekyll version. Use this instead:
bundle update github-pages