sudo apt install ruby-full build-essentials
sudo gem install bundler
bundle install
bundle exec jekyll serve --host 0.0.0.0 --incremental
Your development site will be served locally from http://localhost:4000.
Alternatively, if you want to be able to access the dev server from another machine on your LAN:
# open the firewall to tcp connections on port 4000
sudo ufw allow 4000/tcp
# run the server
bundle exec jekyll serve --host `hostname` --incremental
# close the firewall
sudo ufw delete allow 4000/tcp