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 [Gem-
       file(5)][Gemfile(5)]  and  installed   via   bundle   install(1)   bun-
       dle-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)   bun-
       dle-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 bun-
       dle 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  pro-
	   grams 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 require-
	   ments 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 lock-
       file and the Gemfile do not match. Bundler needs the Gemfile to	deter-
       mine  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  she-
       bang,  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  optimiza-
       tion 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  ver-
       sion  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  Gem-
       file.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).



				 January 2020			BUNDLE-EXEC(1)