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

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 Gem-
file(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)   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

Shelling out
    When shelling out (using the system or backticks methods, for example),
    Bundler's environment changes will propogate to the  subshell  environ-
    ment. If you desire to shell out without Bundler's environment changes,
    simply employ the with_clean_env method. It will restore  all  environ-
    ment  variables  to  what  they  were before Bundler was activated. For
    example:

        Bundler.with_clean_env do
          %xbrew 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 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 -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).

                         September 2012                  BUNDLE-EXEC(1)