demo2.rb

require 'rubygems'
require 'deep_merge'

# one level
x = {
  :first_level => {
    :one => 1
  }
}

y = {
  :first_level => {
    :two => 2
  }
}

p x.deep_merge!(y)

# two
x = {
  :first_level => {
    :second_level => {
      :one => 1
    }
  }
}

y = {
  :first_level => {
    :second_level => {
      :two => 2
    }
  }
}

p x.deep_merge!(y)

# conflicts, y wins
x = {
  :test => {
     :one => {
        1 => 1,
        2 => 1,
        3 => 1
    }
  }
}

y = {
  :test => {
    :one => {
      1 => 2,
      3 => 4,
      5 => 6
    }
  }
}

p x.deep_merge!(y)

gistfile2.txt

{:first_level=>{:one=>1, :two=>2}}
{:first_level=>{:second_level=>{:one=>1, :two=>2}}}
{:test=>{:one=>{5=>6, 1=>2, 2=>1, 3=>4}}}