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)