RubyGems の設定ファイル

オプションのデフォルトを設定するには、~/.gemrc か /etc/gemrc を作成する

$ gem help environment
(省略)
Command line argument defaults and some RubyGems defaults can be set in
~/.gemrc file for individual users and a /etc/gemrc for all users.  A gemrc
is a YAML file with the following YAML keys:

  :sources: A YAML array of remote gem repositories to install gems from
  :verbose: Verbosity of the gem command.  false, true, and :really are the
            levels
  :update_sources: Enable/disable automatic updating of repository metadata
  :backtrace: Print backtrace when RubyGems encounters an error
  :bulk_threshold: Switch to a bulk update when this many sources are out of
                   date (legacy setting)
  :gempath: The paths in which to look for gems
  gem_command: A string containing arguments for the specified gem command

Example:

  :verbose: false
  install: --no-wrappers
  update: --no-wrappers
(省略)
$ less ~/.gemrc
:sources: 
- http://gems.rubyforge.org/
- http://gems.github.com/
install: --no-rdoc --no-ri
update: --no-rdoc --no-ri

RubyGems User Guide | RubyGems Manuals