Simple hostfile manager

domain.rb

#!/usr/bin/env ruby
#
# Simple hostfile manager
#
# Only tested on OSX
#
# Usage:
#
# To list defined entries in the hostfile, call:
#
#   sudo domain list [FILTER]
# 
# If FILTER is not supplied, all entries will be listed. If it is supplied, list will only display entries matching the filter
#
# To add an entry to the hostfile, call:
#
#   sudo domain add NAME [IP]
#
# IP is optional and will default to 127.0.0.1 if not specified
#
# To remove an entry to the hostfile, call:
#
#   sudo domain remove NAME
#
#
# Examples:
#   >> sudo domain add example.com
#   Added example.com at 127.0.0.1 to /etc/hosts
#   >> sudo domain add subdomain.example.com 127.0.0.1
#   Added subdomain.example.com at 127.0.0.1 to /etc/hosts
#   >> sudo domain list example
#   127.0.0.1 => example.com
#   127.0.0.1 => subdomain.example.com
#   >> sudo domain remove subdomain.example.com
#   Removed subdomain.example.com from /etc/hosts
#
#
# LICENSE
# 
# Copyright (c) 2010 Marcin Bunsch <marcin@applicake.com>
# 
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
# 
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
#
abort "You need to have root access to manage domains, please run 'sudo domain#{ARGV.size > 0 ? ' ' + ARGV.join(' ') : ''}'" unless ENV['SUDO_USER'] 

class HostFile
  HOSTFILE     = '/etc/hosts'
  SEPARATOR    = '  '
  UNREMOVABLES = ['localhost']
  HEADER       = <<-STR 
##
# Host Database
#
# localhost is used to configure the loopback interface
# when the system is booting.  Do not change this entry.
##
STR
  
  attr_accessor :entries

  def initialize
    self.entries = File.open(HOSTFILE).read.split("\n").collect do |line|
      next if line.strip[0] == 35
      next if line.strip == ''
      line.strip.split(/\s+/)
    end.compact
  end

  def filename
    HOSTFILE
  end
  
  def has?(name)
    entries.find { |entry| entry[1] == name }
  end
  
  def removable?(name)
    !UNREMOVABLES.include?(name)
  end
  
  def save
    content = ([HEADER] + entries.compact.collect { |entry| "#{entry[0]}#{SEPARATOR}#{entry[1]}"}).join("\n")
    f = File.open(HOSTFILE, 'w')
    f.write(content)
    f.close
  end
  
  def add(name, ip = "127.0.0.1")
    self.entries << [(ip || "127.0.0.1"), name]
  end
  
  def add!(name, ip = "127.0.0.1")
    add(name, ip)
    save
  end
  
  def remove(name)
    self.entries.reject! { |entry| entry[1] == name }
  end

  def remove!(name)
    remove(name)
    save
  end

end

hostfile = HostFile.new

case command = ARGV[0]
  when 'list'
    filter = ARGV[1]
    hostfile.entries.each do |entry|
      if !filter or (filter and entry[1].match(filter))
        puts "#{entry[0]} => #{entry[1]}"
      end
    end
  when 'add'
    name = ARGV[1]
    abort "#{name} is already in #{hostfile.filename}" if hostfile.has?(name)
    hostfile.add!(name, ARGV[2])
    puts "Added #{hostfile.entries.last[1]} at #{hostfile.entries.last[0]} to #{hostfile.filename}"
  when 'remove'
    name = ARGV[1]
    abort "#{name} is not in #{hostfile.filename}" unless hostfile.has?(name)
    abort "#{name} cannot be removed from #{hostfile.filename}" unless hostfile.removable?(name)
    hostfile.remove!(name)
    puts "Removed #{name} from #{hostfile.filename}"
end