class String
  # returns the string enclosed in double quotes.
  # all characters in the string that could be harmful will be escaped.
  # 
  # e.g. 
  # 'test'.shell_escape_double_quotes   # => "test"
  # '$\\'"`'.shell_escape_double_quotes # => "\$\\'\"\`"
  #
  # This should work in al POSIX compatible shells.
  #
  # see: http://www.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html#tag_02_02_03
  def shell_escape_double_quotes
    '"'+gsub(/\\|"|\$|`/, '\\\\\0')+'"'
  end unless method_defined?(:shell_escape_double_quotes)
  
  # stolen from active_support/inflector
  # TODO require "active_support/core_ext/string/inflections" when 3.0 is released
  def underscore
    gsub(/::/, '/').
    gsub(/([A-Z]+)([A-Z][a-z])/,'\1_\2').
    gsub(/([a-z\d])([A-Z])/,'\1_\2').
    tr("-", "_").
    downcase
  end unless method_defined?(:underscore)
end