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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).
September 2019 BUNDLE-EXEC(1)
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