a command line tool to help add / delete / list / search hosts file.

hosts.rb

#!/usr/bin/env ruby
# encoding: utf-8

require 'optparse'
require 'fileutils'

@options = {}
@hosts_path = '/private/etc/hosts'

OptionParser.new { |opts|
  opts.banner = 'Usage: [options]'

  opts.on('-a', '--add domain', 'domain will be added') do |domain|
    @options[:method] = 'add'
    @options[:domain] = domain
  end

  opts.on('-d', '--del domain', 'domain will be deleted') do |domain|
    @options[:method] = 'del'
    @options[:domain] = domain
  end

  opts.on('-i', '--ip ip', 'ip. if missing when adding domain, will be 127.0.0.1; if presented when deleting domain, only the domain that macthes this ip will be deleted') do |ip|
    @options[:ip] = ip
  end

  opts.on('-l', '--list [keyword]', 'list of domains and ip that matches search keyword') do |keyword|
    @options[:search] = true
    @options[:keyword] = keyword
  end

  opts.on_tail('-h', '--help', 'list of arguments') do
    puts opts
    exit
  end

  opts.parse!
}

def manipulation (ip, domain, method)
  contents = File.read @hosts_path

  if method == 'add'
    ip ||= '127.0.0.1'

    File.open(@hosts_path, "a:UTF-8") do |file|
      domain.split(' ').each do |d|
        file.puts ip + ' ' + d + "\n"
        puts "#{ip} is added to #{d}."
      end
    end
  else
    new_contents = []

    domains = domain.split(' ').join('|')
    re = nil
    re_str = "(#{domains})"
    re_str = "#{ip}\s+" + re_str if ip

    re_str.gsub! '.', '\.'
    re = /#{re_str}/

    contents.each_line do |line|
      new_contents.push(line) unless re.match line
    end

    File.open(@hosts_path, "w:UTF-8") do |file|
      file.truncate 0
      file.write new_contents.join
    end

    puts "#{domain} is/are deleted."
  end
end

def list (keyword)
  File.open(@hosts_path, "r:UTF-8") do |file|
    file.read.each_line do |line|
      puts line if line.index keyword.to_s
    end
  end
end

if @options[:search]
  list @options[:keyword]
else
  manipulation @options[:ip], @options[:domain], @options[:method]
end