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How to Install Gems in Ruby on Rails

2:21 with Jason Seifer

A Ruby gem is a library you can use in your Ruby applications. It's really easy to install a gem. You just need to know the name of the gem you want to install. In this Treehouse Quick Tip, Ruby teacher Jason shows you how to install the Bundler gem.

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    [treehouse presents]

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    [Quick Tips] [How to Install Gems in Ruby on Rails] [by Jason Seifer]

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    Hi, I'm Jason.

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    In this treehouse quick tip, we're going to talk about how to install Ruby gems.

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    A Ruby gem is a library that you can use in your Ruby applications.

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    It's really easy to install a gem.

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    You just need to know the name of the gem that you want to install.

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    In this example, I'm going to install the Bundler gem.

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    The way to install a gem is by typing the word "gem" followed by a space

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    followed by the word "install" and then the name of the gem that you want to install.

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    I'm going to install the Bundler gem.

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    After that, press "enter" and then Ruby gems will go out, download the proper gem,

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    and install it onto your system.

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    If you get a message about not having the proper permissions to install a gem,

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    you can use the "sudo" command to install the correct gem.

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    You would use the "sudo" command on systems where your version of Ruby is installed

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    globally rather than on a system like RVM or RBN where you can install gems locally

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    to your own home directory.

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    I'm going to install another gem called Money.

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    The gem install command will also install any needed dependencies of a gem.

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    For example, the Money gem requires the i18n gem and also the json gems.

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    Once you install a gem, it's really easy to use.

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    First, require Ruby gems, then you can also require the gem that you just installed.

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    And there you go.

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    There's one other way to install gems, and that would be from a gem file.

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    A gem file will be in a Ruby on Rails application or actually any Ruby application

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    that uses Bundler.

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    You specify the gem dependencies in the gem file, and then once you do that,

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    you can type the word "bundle install" and then Bundler will go through and install

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    all of these gems for you.

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    As you can see, it's very easy to install and use Ruby gems.

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    The hardest part is finding good ones to install.

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    Luckily, there are sites like RubyGems.org and GitHub for that.

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    Happy coding!

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