I searched the Internet in vain for examples of using the Ruby i18n gem outside of Rails apps.

Below is a minimal example: the aim is (as usual) to produce a greeting - this time in English and Italian.

Installation

$ gem install i18n

The t method

The most common use of i18n is via I18n.translate which has an abbreviated alias I18n.t.

Translations

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en:
  hello world: Hello World!

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it:
  hello world: Ciao Mondo!

These translations can be accessed as follows: I18n.t( ‘hello world’ )

That will use the current locale setting. You can change it as follows: I18n.locale = :it

The Program

After loading the i18n gem, set up I18n.load_path before attempting to retrieve any transaltions.

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require 'rubygems' if RUBY_VERSION < '1.9'
require 'i18n'

I18n.load_path = ['en.yml', 'it.yml']

puts 'In English...'
I18n.locale = :en
puts I18n.t('hello world')

puts 'In Italian...'
I18n.locale = :it
puts I18n.t('hello world')

The result:

$ ruby salutation.rb
In English...
Hello World!
In Italian...
Ciao Mondo!