Every time you change your Gemfile then you might adding/removing any dependancies in your application.
will install gems for you.
The output may look like
$ bundle install
Fetching source index for http://rubygems.org/
Using rake (0.8.7)
Installing abstract (1.0.0)
Your bundle is complete! Use `bundle show [gemname]` to see where a
bundled gem is installed.
You can specify groups for special environments
$ bundle install --without development test
$ bundle install --without test
You can specify installation directory for your gems.
This will install all the gems into tmp/bundle folder
$ bundle install --path tmp/bundle
You can check your applications bundler config.
$ bundle config
Settings are listed in order of priority. The top value will be used.
Set for your local app (/Users/arunagw/foobar/.bundle/config): "1"
Set for your local app (/Users/arunagw/foobar/.bundle/config): "tmp/bundle"
For more details about bundler you can checkout http://gembundler.com/
And also http://railscasts.com/episodes/201-bundler