NAME

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

SYNOPSIS

       bundle exec [--keep-file-descriptors] command

DESCRIPTION

       This command executes the command, making all gems specified in the [Gemfile(5)][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)][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.

OPTIONS

       --keep-file-descriptors
              Exec in Ruby 2.0 began discarding non-standard file descriptors. When this flag  is  passed,  exec
              will revert to the 1.9 behaviour of passing all file descriptors to the new process.

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

       Finally,  bundle exec also implicitly modifies Gemfile.lock if the lockfile and the Gemfile do not match.
       Bundler needs the Gemfile to determine things such as a gem´s groups, autorequire, and  platforms,  etc.,
       and  that  information  isn´t stored in the lockfile. The Gemfile and lockfile must be synced in order to
       bundle exec successfully, so bundle exec updates the lockfile beforehand.

   Loading
       By default, when attempting to bundle exec to a file with a ruby shebang, Bundler will  Kernel.load  that
       file  instead of using Kernel.exec. For the vast majority of cases, this is a performance improvement. In
       a rare few cases, this could cause some subtle side-effects (such as dependence on the exact contents  of
       $0 or __FILE__) and the optimization can be disabled by enabling the disable_exec_load setting.

   Shelling out
       Any  Ruby code that opens a subshell (like system, backticks, or %x{}) will automatically use the current
       Bundler environment. If you need to shell out to a Ruby command that is not part of your current  bundle,
       use  the  with_clean_env  method  with  a block. Any subshells created inside the block will be given the
       environment present before Bundler was activated. For example, Homebrew commands run Ruby, but don´t work
       inside a bundle:

           Bundler.with_clean_env do
             `brew install wget`
           end

       Using  with_clean_env  is  also  necessary  if  you  are  shelling out to a different bundle. Any Bundler
       commands run in a subshell will inherit the current Gemfile, so commands that need to run in the  context
       of a different bundle also need to use with_clean_env.

           Bundler.with_clean_env do
             Dir.chdir "/other/bundler/project" do
               `bundle exec ./script`
             end
           end

       Bundler provides convenience helpers that wrap system and exec, and they can be used like this:

           Bundler.clean_system(´brew install wget´)
           Bundler.clean_exec(´brew install wget´)

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 -rrubygems -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).

                                                  December 2019                                   BUNDLE-EXEC(1)