Ruby is a dynamic, interpreted, open source programming language with a focus on simplicity and productivity.
The version of Ruby you need to install depends on your requirements. If you are supporting a legacy application, install Ruby 1.9 or 1.8 as necessary. If you are starting a new project, Ruby 2.0 is recommended. Below is a summary of the available versions and how to get them.
To install Ruby 2.0, install RubyGems.. Ruby 2.0 includes
To install Ruby 1.9, install AUR. Ruby 1.9 includes RubyGems.AUR from the
To install Ruby 1.8, install AUR. Ruby 1.8 does not include RubyGems. Instead, it is available through the AUR package.AUR from the
To make documentation available through the included
ri command-line tool, install .
You can then query the docs with:
ri Array.pop etc. (much like man-pages)
gem is a package manager for Ruby modules (called Gems), somewhat comparable to what pacman is to Arch Linux. The gem command will be installed if you followed the installation instructions above.
Before you use Gems, you need to add
$(ruby -rubygems -e "puts Gem.user_dir")/bin to your
To see what gems are installed:
$ gem list
To get information about a gem:
$ gem spec gem_name
gem list and
gem spec use the
--local option, which forces gem to search only the local system. This can be overridden with the
--remote flag. Thus, to search for the mysql gem:
$ gem list --remote mysql
To install a gem:
$ gem install mysql
The process can be sped up somewhat if you do not need local documentation:
$ gem install mysql --no-rdoc --no-ri
To update all installed gems:
$ gem update
Running as normal user
When running gem as a normal user, gems are installed into
~/.gem instead of system-wide. This is considered the best way to manage gems on Arch. Unfortunately, not all gems are happy with being installed in this way, and might insist on being installed by root, especially if they have native extensions (compiled C code). This per-user behavior is enabled via
/etc/gemrc and can be overridden by a
Running as root
When running as root, the gems will be installed into
/root/.gems and will not be installed to
Bundler solves these problems to some extent by packaging gems into your application. See the section below on using bundler.
Bundler allows you to specify which gems your application depends upon, and optionally which version those gems should be. Once this specification is in place, Bundler installs all required gems (including the full gem dependency tree) and logs the results for later inspection. By default, Bundler installs gems into a shared location, but they can also be installed directly into your application. When your application is run, Bundler provides the correct version of each gem, even if multiple versions of each gem have been installed. This requires a little bit of work: applications should be called with
bundle exec, and two lines of boilerplate code must be placed in your application's main executable.
To install Bundler:
$ gem install bundler
By default, Bundler installs gems system-wide, which is contrary to the behaviour of gem itself on Arch. To correct this, add the following to your
To start a new bundle:
$ bundle init
Gemfile in the current directory (created by bundle init) and list your required gems:
gem "rails", "3.2.9" gem "mysql"
Run the following to install gems into
$ bundle install
Alternatively, run the following to install gems to
.bundle in the working directory:
$ bundle install --path .bundle
Don't forget to edit your main executable:
#!/usr/bin/env ruby # "This will automatically discover your Gemfile, and make all of the gems in # your Gemfile available to Ruby." http://gembundler.com/v1.3/rationale.html require 'rubygems' require 'bundler/setup' ...
Finally, run your program:
bundle exec main_executable_name.rb
Managing RubyGems using pacman
Instead of managing gems with
gem, you can use
pacman, or some AUR helper. Ruby packages follow the naming convention ruby-[gemname]. This option provides the following advantages:
- Gems are updated along with the rest of your system. As a result, you never need to run
# pacman -Syusuffices.
- Installed gems are available system-wide, instead of being available only to the user who installed them.
If a gem is not available in the repositories, you can useAUR to automatically create a package, which can then be installed by pacman.