Binstubs, short for “binary stubs,” are small executable scripts that act as wrappers around Ruby executables or scripts. They are commonly used in Ruby projects managed with Bundler to provide a convenient way to execute commands without needing to prepend them with bundle exec.

When you run bundle install --binstubs Bundler will create a bin folder full of any executables that your gems are capable of.

When I ran bundle install --binstubs on the jekyll project for this website I got results of:

% bundle install --binstubs
[DEPRECATED] The --binstubs option will be removed in favor of `bundle binstubs --all`
Using public_suffix 5.0.4
Using addressable 2.8.5
Using bundler 2.2.22
Using colorator 1.1.0
Using concurrent-ruby 1.2.2
Using eventmachine 1.2.7
Using http_parser.rb 0.8.0
Using em-websocket 0.5.3
Using ffi 1.16.3
Using forwardable-extended 2.6.0
Using i18n 1.14.1
Using sassc 2.4.0
Using jekyll-sass-converter 2.2.0
Using rb-fsevent 0.11.2
Using rb-inotify 0.10.1
Using listen 3.8.0
Using jekyll-watch 2.2.1
Using rexml 3.2.6
Using kramdown 2.4.0
Using kramdown-parser-gfm 1.1.0
Using liquid 4.0.4
Using mercenary 0.4.0
Using pathutil 0.16.2
Using rouge 3.30.0
Using safe_yaml 1.0.5
Using unicode-display_width 1.8.0
Using terminal-table 2.0.0
Using jekyll 4.2.2
Using jekyll-feed 0.17.0
Using jekyll-redirect-from 0.16.0
Using jekyll-seo-tag 2.8.0
Using jekyll-sitemap 1.4.0
Using minima 2.5.1
Using webrick 1.8.1
Bundle complete! 9 Gemfile dependencies, 34 gems now installed.
Use `bundle info [gemname]` to see where a bundled gem is installed.

A new folder was also created:

bin/
 - bundle
 - jekyll
 - kramdown
 - listen
 - rougify
 - safe_yaml

It also added:

+BUNDLE_BIN: "bin"

To the .bundle/config file.