BUNDLE-EXEC(1)							BUNDLE-EXEC(1)



NAME
       bundle-exec - Execute a command in the context of the bundle

SYNOPSIS
       bundle exec command

DESCRIPTION
       This  command  executes	the  command, making all gems specified in the
       Gemfile(5) available to require in Ruby programs.

       Essentially, if you  would  normally  have  run	something  like  rspec
       spec/my_spec.rb,  and  you  want  to use the gems specified in the Gem-
       file(5) and installed via bundle install(1) bundle-install.1.html,  you
       should run bundle exec rspec spec/my_spec.rb.

       Note  that bundle exec does not require that an executable is available
       on your shell's $PATH.

BUNDLE INSTALL --BINSTUBS
       If  you	use  the   --binstubs	flag   in   bundle   install(1)   bun-
       dle-install.1.html,  Bundler  will  automatically  create  a  directory
       (which defaults to app_root/bin)  containing  all  of  the  executables
       available from gems in the bundle.

       After  using --binstubs, bin/rspec spec/my_spec.rb is identical to bun-
       dle exec rspec spec/my_spec.rb.

ENVIRONMENT MODIFICATIONS
       bundle exec makes a number of changes to the  shell  environment,  then
       executes the command you specify in full.

       o   make  sure  that  it's  still  possible to shell out to bundle from
	   inside a command invoked by bundle exec (using $BUNDLE_BIN_PATH)

       o   put	the  directory	containing  executables  (like	rails,	rspec,
	   rackup) for your bundle on $PATH

       o   make  sure  that if bundler is invoked in the subshell, it uses the
	   same Gemfile (by setting BUNDLE_GEMFILE)

       o   add -rbundler/setup to $RUBYOPT, which makes sure  that  Ruby  pro-
	   grams invoked in the subshell can see the gems in the bundle



       It also modifies Rubygems:

       o   disallow loading additional gems not in the bundle

       o   modify  the gem method to be a no-op if a gem matching the require-
	   ments is in the bundle, and to raise a Gem::LoadError if it's not

       o   Define Gem.refresh to be a no-op, since the source index is	always
	   frozen  when  using	bundler,  and  to prevent gems from the system
	   leaking into the environment

       o   Override Gem.bin_path to use the gems in the bundle, making	system
	   executables work

       o   Add all gems in the bundle into Gem.loaded_specs



   Shelling out
       When shelling out (using the system or backticks methods, for example),
       Bundler's environment changes will propogate to the  subshell  environ-
       ment. If you desire to shell out without Bundler's environment changes,
       simply employ the with_clean_env method. It will restore  all  environ-
       ment  variables	to  what  they	were before Bundler was activated. For
       example:



	   Bundler.with_clean_env do
	     `brew install wget`
	   end



RUBYGEMS PLUGINS
       At present,  the  Rubygems  plugin  system  requires  all  files  named
       rubygems_plugin.rb  on the load path of any installed gem when any Ruby
       code requires rubygems.rb. This includes executables installed into the
       system, like rails, rackup, and rspec.

       Since  Rubygems	plugins can contain arbitrary Ruby code, they commonly
       end up activating themselves or their dependencies.

       For instance, the gemcutter 0.5 gem depended on json_pure. If  you  had
       that  version of gemcutter installed (even if you also had a newer ver-
       sion without this problem), Rubygems would activate gemcutter  0.5  and
       json_pure <latest>.

       If your Gemfile(5) also contained json_pure (or a gem with a dependency
       on json_pure), the latest version on your system  might	conflict  with
       the  version  in  your Gemfile(5), or the snapshot version in your Gem-
       file.lock.

       If this happens, bundler will say:



	   You have already activated json_pure 1.4.6 but your Gemfile
	   requires json_pure 1.4.3. Consider using bundle exec.



       In this situation, you almost certainly want to remove  the  underlying
       gem  with  the problematic gem plugin. In general, the authors of these
       plugins (in this case, the gemcutter gem) have released newer  versions
       that are more careful in their plugins.

       You can find a list of all the gems containing gem plugins by running



	   ruby -rubygems -e "puts Gem.find_files('rubygems_plugin.rb')"



       At the very least, you should remove all but the newest version of each
       gem plugin, and also remove all gem plugins that you aren't using  (gem
       uninstall gem_name).



				 November 2010			BUNDLE-EXEC(1)
