When you run
rspec within your project’s directory, rbenv can ensure that it
will get executed with the Ruby version configured for that project. However,
nothing will ensure that the right version of RSpec gets activated; in fact,
RubyGems will simply activate the latest RSpec version even if your project
depends on an older version. In the context of a project, this is unwanted
This is why
bundle exec <command> is so often needed. It ensures the right
versions of dependencies get activated, ensuring a consistent ruby runtime
bundle exec is a pain to always have to write.
Bundler can install binstubs in your project for all executables contained in the current bundle.
bundle install --binstubs
This creates, among others,
./bin/rspec (simplified version shown):
RSpec can now be easily called with
If you go one step further and prepend
./bin to your $PATH, you can simply
rspec instead of
bin/rspec. This is recommended so that you are able to
launch RSpec the same way in a context of a project and outside of it.
Manually created binstubs
Now that you know that binstubs are simple scripts written in any language and understand their purpose, you should consider creating own binstubs for your project or your local development environment.
For instance, in the context of a Rails application, a manually generated
binstub to run Unicorn could be in
bin/unicorn now ensures that Unicorn will run in the exact same
environment as the application: same Ruby version, same Gemfile dependencies.
This is true even if the binstub was called from outside the app, for instance