Ruby

Ruby is an essential build tool for developing. Many utilities or their installation scripts are built with Ruby language, or the Ruby package manager, RubyGems. For the convenience for versions switching, and with the reason not messing up the native Ruby installed by OS X, we employee rbenv to manage the Ruby versions. An alternative is RVM and rbenv is incompatible with RVM. There is a comic showing you a comparison.

Installing Ruby with rbenv

rbenv works by inserting a directory of shims at the front of your PATH through a process called rehashing. rbenv maintains shims in that directory to match every Ruby command across every installed version of Ruby—irb, gem, rake, rails, ruby, and so on.

Installing rbenv

  1. Install the rbenv suite which includes rbenv—The main utility, ruby-build—provides the rbenv install/uninstall/build command, rbenv-default-gems—hooks into rbenv install command to automatically install gems every time you install a new version of Ruby.

     brew install rbenv ruby-build rbenv-default-gems

  2. Add rbenv plugin into oh-my-zsh. It initilize rbenv automatically when you are logining shell and changes the defualt rbenv variables.

    Check Zsh plugins: rbenv section:

    Plugin rbenv changes the defualt rbenv variables and exports them, provides some useful related function, explicitly tells rbenv to use Zsh, and initilize the rbenv automatically.

    With the reason you install rbenv by Homebrew, this plugin will point the rbenv directory under Homebrew formulea repository, instead of ~/.rbenv, to RBENV_ROOT.

  3. Reopen a new terminal tab or restart your shell for sourcing settings.

Install Ruby

  1. Get the versions of Ruby:

     rbenv install --list

  2. Install the Ruby version:

     rbenv install <version>

  3. Rehash for shims work:

     rbenv rehash

  4. Set the Ruby version to replace the system built-in version:

     rbenv global <version>

  5. Check the installed ruby versions or the current working version

     rbenv versions
 rbenv version

Specifing the Ruby running version for shims

When you execute a shim, rbenv specifies the running version of Ruby for this shim by reading a specified env variable or some files in order:

  1. RBENV_VERSION environment variable.
  2. The first .ruby-version file in the directory of the target script or in the script's parent directories.
  3. The first .ruby-version file in the current working directory or the parent directories.
  4. The global .rub-version file located in the directory is pointed by RBENV_ROOT variable.

Note:

  1. rbenv local <version> changes the content of .ruby-version file under current working directory.
  2. rbenv global <version> changes the content of .ruby-version file under RBENV_ROOT.
  3. --unset option cancel the version specifying.

Binding gems with each new Ruby version

rbenv-default-gems automatically installs the gems listed in $(rbenv root)/default-gems file every time you successfully install a new version of Ruby with rbenv install.

A Sample file:

# One per line
bundler
rbenv-gem-rehash
# Specifing a version
bcat ~>0.6
# Specifing prerelease version
rails --pre

RubyGems

RubyGems is a package management framework for Ruby. This gem is an update for the RubyGems software. You must have an installation of RubyGems before this update can be applied.

RubyGems is bounded to Ruby by default, to upgrade to the latest RubyGems, run:

gem update --system

Usages

# List installed or remote gems with/without details:
gem list [-r] [-d] [REGEXP]
# Install a gem with/without document:
gem install <gem> --no-document
# Show outdated gems
gem outdated
# Update installed gems or a particular gem:
gem update [<gem>]
# Clean up old versions of installed gems
gem cleanup [--dryrun]
# Show the dependencies of an installed gem, or reverse dependencies
gem dependency [-R]

Note: For a faster gem installation, add option --no-document disable documentation generation. Add a config into ~/.gemrc make it be default for each installation command:

echo 'gem: --no-document' >> ~/.gemrc

Tab-completion

Check Zsh plugins: gem section:

Plugin gem for Zsh enables the tab-completion feature.

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