Bash

krzysztof@samsung:~$ ruby test.rb test.csv 10.39.30.252
"S2774"
krzysztof@samsung:~$ ruby test.rb test.csv 10.39.30.255
:unknown
krzysztof@samsung:~$ 

location.rb

#!/usr/bin/env ruby

require 'csv'

class Location
  attr_reader :file

  def initialize(file)
    @file  = file

    @data = Hash.new do |h,k|
      h[k] = { :location => :unknown, :device_type => :unknown }
    end

    CSV.read(file).each do |line|
      @data[line.shift] = { :location    => line.shift,
                            :device_type => line.shift }
    end
  end

  def get_location(location)
    @data[location][:location]
  end
end

if $0 == __FILE__
  file, location = ARGV.shift, ARGV.shift

  l = Location.new(file)
  p l.get_location(location)
end

test.csv