Opscode distributes Ohai as a Gem, available from http://gems.opscode.com/. It is a requirement for Chef, so if you have Chef installed, you have Ohai. If you would like to install Ohai separately, for testing or development, read on.
Install Gem
Add Opscode's gem server to your local sources:
Install the Gem.
This will also install Ohai's dependency gems, json, extlib and systemu.
If you're running Windows, we have preliminary support for some platforms. See Installing Ohai on Windows for more information.
Install from Git
We use GitHub for sharing our source code, so to install the source from Git:
Install the gem with rake.
See the README.rdoc included in the repository (or on the GitHub page) for more about Ohai development. Also read about contributing to Opscode projects
