berks:tldr:29f4b

This command is known as the "berks update" command and it is used in the context of Chef's Berkshelf tool. Berkshelf is a dependency manager for Chef cookbooks that helps manage cookbook dependencies in a Chef infrastructure.

The command "berks update" is used to update the cookbooks and their dependencies described in a Berkshelf file. When running the command, it generally updates all the cookbooks in the project. However, in the command you provided, there is a placeholder "${cookbook}" which suggests that the command might be intended to update a specific cookbook.

Assuming you replace "${cookbook}" with the name of a specific cookbook, such as "apache", the command "berks update apache" would update the "apache" cookbook and its dependencies. It fetches the latest versions of the cookbook and its dependencies from their specified sources, such as a Chef Supermarket or a GitHub repository, and updates them in the local cookbook repository.

This command is helpful when you want to ensure that your cookbooks and their dependencies are up to date with the latest versions available. It helps keep your Chef infrastructure current and provides bug fixes, security updates, and new features that may have been released in newer versions of the cookbooks.