To install foo gem to a specified folder, just use --install-dir option, i.e.
$ gem install --install-dir /path/to/gems/folder foo
It helps when:
- one cannot use
bundle install– e.g. if one wants to install bundle gem itself, or wants to install a gem (which is not listed in Gemfile) into the bundle folder sudo gem installcommand fails due to lack of write-permissions for a default installation path
Hope that helps.