Rails instalando plugins

$ script/plugin install -h
Usage: plugin install PLUGIN [PLUGIN [PLUGIN] ...]
Install one or more plugins.

Options:
  -x, --externals                  Use svn:externals to grab the plugin.
                                   Enables plugin updates and plugin versioning.
  -o, --checkout                   Use svn checkout to grab the plugin.
                                   Enables updating but does not add a svn:externals entry.
  -e, --export                     Use svn export to grab the plugin.
                                   Exports the plugin, allowing you to check it into your local repository. Does not enable updates, or add an svn:externals entry.
  -q, --quiet                      Suppresses the output from installation.
                                   Ignored if -v is passed (./script/plugin -v install ...)
  -r, --revision REVISION          Checks out the given revision from subversion or git.
                                   Ignored if subversion/git is not used.
  -f, --force                      Reinstalls a plugin if it's already installed.

You can specify plugin names as given in 'plugin list' output or absolute URLs to 
a plugin repository.

Ejemplos

$ script/plugin install https://github.com/gunark/rubycas-client.git
Initialized empty Git repository in /home/gomix/Ruby/Rails/cas-client/vendor/plugins/rubycas-client/.git/
remote: Counting objects: 71, done.
remote: Compressing objects: 100% (65/65), done.
remote: Total 71 (delta 4), reused 47 (delta 1)
Unpacking objects: 100% (71/71), done.
From https://github.com/gunark/rubycas-client
 * branch            HEAD       -> FETCH_HEAD