See install command help.

Install all gems listed in Gemfile.

$ bundle install
$ # Equivalent but less clear.
$ bundle

Install using parallel processing for faster performance.

$ bundle install --jobs=8

Check paths of installed gems:

$ ls vendor/bundle/ruby/2.7.0/gems
addressable-2.7.0           jekyll-feed-0.15.1          minima-2.5.1
colorator-1.1.0             jekyll-sass-converter-1.5.2 pathutil-0.16.2
...

Arguments

Summary of args I find useful.

Arg Description
--quiet Do not print progress information to the standard output. Instead, Bundler will exit using a status code ($?).
--gemfile=PATH Specify path to a Gemfile. Defaults to the file in the current working directory.
--jobs=[<number>], -j[<number>] The maximum number of parallel download and install jobs. The default is 1. This seems to be popular in CI installs.

Deprecated flags

Note that --frozen, --clean and --deployment flags are marked as deprecated in the CLI help.

Production install - you might see this used and it still works in Bundler 2, but it is deprecated.

$ bundle install --frozen --deployment

The CLI also warns not to use --with GROUP for install groups.

Install groups of dependencies

See the Groups cheatsheet,