Bundler
###bundle - Ruby Dependency Management
Bundler manages an application’s dependencies through its entire life across many machines systematically and repeatably.
Bundler 可根据Gemfile文件安装,更新，执行，调用gem。
####PRIMARY COMMANDS bundle install(1) bundle-install.1.html Install the gems specified by the Gemfile or Gemfile.lock
bundle update(1) bundle-update.1.html
Update dependencies to their latest versions
bundle package(1) bundle-package.1.html
Package the .gem files required by your application into the
vendor/cache directory
bundle exec(1) bundle-exec.1.html
Execute a script in the context of the current bundle
bundle config(1) bundle-config.1.html
Specify and read configuration options for bundler
####gem安装顺序
Gems will be installed to your default system location for gems. While installing gems, Bundler will check vendor/cache and then your system’s gems. If a gem isn’t cached or installed, Bundler will try to install it from the sources you have declared in your Gemfile.
通过bundler，Gems会被安装在本地机器，当安装gems时，Bundler首先检查vendor/cache目录，然后检查系统的gems。如果这个gem还没有被缓存或者安装，那么系统将从Gemfile的gem源里安装。
Install your dependencies, even gems that are already installed to your system gems, to a location other than your system’s gem repository. In this case, install them to vendor/bundle.
$ bundle install --path vendor/bundle查看帮助
$ bundle --help install