Ruby Primer

Ruby Gems

Gem is the package manager for Ruby. Each language has one or more package managers - Python uses pip, and Javascript uses npm. Ruby packages are called gems. To install the rubocop gem, for example, you can type the following into the command line.

gem install rubocop

Verify installation

which rubocop

Bundler

Bundler provides a consistent environment for Ruby projects by tracking and installing the exact gems and versions that are needed. - Bundler.io

Using Bundler you can install a list of Ruby gems from a Gemfile. Bundler tries to make sure that you have the proper version of all dependencies. Using bundler is usually as simple as

bundle install

Yarn

Yarn is a package manager for NodeJS. Check out this article to install Yarn on Ubuntu 18.04. To install and upgrade node modules,

yarn install
yarn upgrade