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 Gemfile(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) bundle-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 bundle 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.

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

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

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

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

       It also modifies Rubygems:

       •   disallow loading additional gems not in the bundle

       •   modify the gem method to be a no-op if a gem matching the requirements is in the bundle, and to raise
           a Gem::LoadError if it´s not

       •   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

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

       •   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 propagate to the subshell environment. If you desire to  shell  out  without  Bundler´s  environment
       changes,  simply employ the with_clean_env method. It will restore all environment 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 version 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
       Gemfile.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).

                                                   April 2013                                     BUNDLE-EXEC(1)