After you’ve configured Lerna and after adding at least one package, you can run `lerna bootstrap`.
The Lerna bootstrap command looks at all your packages in the package directory and resolves their dependencies. If you have cross dependencies like one of your packages depends on another one of your packages, Lerna bootstrap takes care of that and creates a symlink to the dependency in the packages `node_modules` directory.
…that it can be pretty tedious to manage a huge amount of related projects in separate repositories. The Babel repository includes more than 100 separate npm packages, maintaining every one of those packages in it’s own Git repository would be an enormous overhead and not very practical.
… which would be capable of handling version control systems containing multiple terabytes of files, Google built there own proprietary system named Piper to vend this extraordinary large codebase. Because of the sheer file size of the system, Google software developers are using so called Clients in the Cloud to access Piper.