# Ruby

Ruby is a dynamic, interpreted, open source programming language with a focus on simplicity and productivity.

## Installing Ruby

For the latest version of Ruby, install the ruby package. It includes RubyGems.

### Older versions

- For Ruby 2.2, install the ruby2.2AUR package.
- For Ruby 2.1, install the ruby2.1[broken link: archived in aur-mirror] package.
- For Ruby 2.0, install the ruby2.0AUR package.

### Multiple versions

If you want to run multiple versions on the same system (e.g. 2.0.0-p0 and 1.9.3-p392), the easiest way is to use RVM, chrubyAUR or rbenv.

### Documentation

To make documentation available through the included `ri` command-line tool, install ruby-docs. You can then query the docs with: `ri Array`, `ri Array.pop` etc. (much like man-pages)

## RubyGems

RubyGems is a package manager for Ruby modules (called gems), somewhat comparable to what pacman is to Arch Linux. It is included in the ruby package.

### Setup

Before you use RubyGems, you should add `$(ruby -e "print Gem.user_dir")/bin` to your `$PATH`. You can do this by adding the following line to `~/.bashrc`:

    PATH="$(ruby -e 'print Gem.user_dir')/bin:$PATH"

This is required for executable gems to work without typing out the full location, although libraries will work without having to modify your path.

If the method above does not work, you can try adding these lines at the end of your shell configuration file instead:

     #Setting the GEM_PATH and GEM_HOME variables may not be necessary, check 'gem env' output to verify whether both variables already exist
     GEM_HOME=$(ls -t -U | ruby -e 'puts Gem.user_dir')
     GEM_PATH=$GEM_HOME
     export PATH=$PATH:$GEM_HOME/bin

### Usage

To see what gems are installed:

    $ gem list

To get information about a gem:

    $ gem spec gem_name

By default, `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-document

Note: This can be made the default option by configuring the following `~/.gemrc` file:

    ~/.gemrc

    gem: --no-document

To update all installed gems:

    $ gem update

### Installing gems per-user or system-wide

By default in Arch Linux, when running `gem`, gems are installed per-user (into `~/.gem/ruby/`), instead of system-wide (into `/usr/lib/ruby/gems/`). This is considered the best way to manage gems on Arch, because otherwise they might interfere with gems installed by Pacman.

Gems can be installed system wide by running the `gem` command as root, appended with the `--no-user-install` flag. This flag can be set as default by replacing `--user-install` by `--no-user-install` in `/etc/gemrc` (system-wide) or `~/.gemrc` (per-user, overrides system-wide).

Bundler solves these problems to some extent by packaging gems into your application. See the section below on using bundler.

### 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 `~/.bashrc`:

    export GEM_HOME=$(ruby -e 'print Gem.user_dir')

To start a new bundle:

    $ bundle init

Then edit `Gemfile` in the current directory (created by bundle init) and list your required gems:

    Gemfile

    gem "rails", "3.2.9"
    gem "mysql"

Run the following to install gems into `GEM_HOME`:

    $ 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://bundler.io/rationale.html
    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 `gem update`: `# pacman -Syu` suffices.
- Installed gems are available system-wide, instead of being available only to the user who installed them.

If a gem is not available in AUR, you can use gem2archAUR or pacgemAUR to automatically create a package, which can then be installed by pacman.

#### Quarry

Quarry is an opensource tool (GPL3 license) that allows to maintain rubygems binary repository for Arch Linux, as an easier alternative to building packages manually from the AUR. The source is hosted at github.

The repository is maintained by Arch developer anatolik at http://pkgbuild.com/~anatolik/quarry/, and is currently for the x86_64 architecture only. It contains many popular gems and new gems can be added upon request.

See Unofficial user repositories#quarry to enable it.

Then install required gem `# pacman -S ruby-$gemname`.

If you have general questions - send it at the project announcement https://bbs.archlinux.org/viewtopic.php?id=182729
If you have bugreports or code improvements - file at github https://github.com/anatol/quarry

## See also

- Ruby on Rails
- Ruby - http://ruby-lang.org/
- Bundler - http://bundler.io/
- why's (poignant) Guide to Ruby
- [http://ruby.learncodethehardway.org/ Learn Ruby The H

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- Programming languages

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