ruby/man/bundle-exec.1.txt

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



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.

       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
           programs 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
           requirements  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



       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).



                                   June 2020                    BUNDLE-EXEC(1)