Updated version of https://gist.github.com/r-brown/a0b50d56cfb3596e0d17

gistfile1.txt

# Install Homebrew.
$ su ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

# Show brew's commands.
$ brew help

# Check current user.
$ echo $(whoami)

# Grant access to the folders.
$ sudo chown -R $(whoami) /usr/local
$ sudo chown -R $(whoami) /Library/Caches/Homebrew/

# Uninstall brew's version of Ruby.
$ brew uninstall ruby

# Install rbenv.
$ brew update
$ brew install rbenv ruby-build

# Add ~/.rbenv/bin to your $PATH for access to the rbenv command-line utility.
$ echo 'export PATH="$HOME/.rbenv/bin:$PATH"' >> ~/.bash_profile

# Add rbenv init to your shell to enable shims and autocompletion.
$ echo 'eval "$(rbenv init -)"' >> ~/.bash_profile

# Install ruby via rbenv.
$ rbenv install 2.2.3
$ rbenv global 2.2.3
$ rbenv versions

# Check install paths.  The paths should point at /Users/you/.rbenv/shims, not /usr/bin.
$ which ruby
$ which gem
$ which jekyll  # jekyll hasn't been installed at this point.

# Rehash the shims.
$ rbenv rehash

# Check Ruby version and environment.
$ ruby --version
$ gem env

# Install bundler.
$ gem install bundler

# Go to the project folder.
$ cd <project folder>

# Install / update gems.
$ bundle install
  or
$ bundle update

# Show installed jekyll.
$ bundle show jekyll

# Serve jekyll pages.
$ bundle exec jekyll serve --drafts --config _config.yml,_config_dev.yml