hosts.rb

#! /usr/bin/ruby

class HostsFile
  attr_accessor :lines

  def initialize(path = '/etc/hosts')
    @file     = File.open(path, 'r')
    @entries  = []

    parse
  end

  def parse
    @file.each_line do |line|
      unless invalid_line?(line)
        @entries << parse_line(line)
      end
    end
  end

  def includes?(name)
    if (entries = fuzzy_entry_match(name)).empty?
      puts "No entries found under the name '#{name}'"
    else
      puts "#{entries.size} entries found:", ''
      entries.each { |e| puts "* #{e}" }
    end
  end

private

  def parse_line(line)
    parts = line.strip!.split(' ')

    HostsEntry.new(parts[0], parts[1])
  end

  def invalid_line?(line)
    line.strip.empty? || line.include?('#')
  end

  def fuzzy_entry_match(name)
    @entries.reject { |l| !l.name.include?(name) }.sort
  end

end

class HostsEntry < Struct.new(:address, :name)

  def to_s
    [ self.address, self.name ].join(' ')
  end

  def <=>(other)
    self.address <=> other.address
  end

end

hosts = HostsFile.new
hosts.includes?(ARGV[0] || '')