Adds a host to the Windows' hosts file

add-host.rb

# It'll append the hosts file with an argument you
# send to it.
#
# For example, if you open 'cmd.exe' and go where this
# script is located:
#
# C:\Users\you> ruby add-host.rb "127.0.0.1 some-website.com"
#
# Your hosts file will have '127.0.0.1 some-website.com' at
# the end.
#
# Of course, you need administrator priviledges when running it.

begin

  # 'ARGV' contains all the things you send to
  # the program when calling it.
  #
  # For example, in your 'cmd.exe':
  #
  # C:\Users\you> ruby add-host.rb "127.0.0.1 some-website.com"
  #
  # ARGV.first will have the string "127.0.0.1 some-website.com"
  if not ARGV.first
    exit
  end	
  
  filename = "C:/Windows/system32/drivers/etc/hosts"
  
  # This block of code will try to open 'filename'
  # and keep it open until it reaches 'end'.
  #
  # That '"a"' is to append things to the end of
  # 'file'.
  #
  File.open(filename, "a") do |file|
  
    # Appending the first argument to the file
    file.puts ARGV.first
  end	
  
  exit
end