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)