Sencha Cmd supports an advanced concept described as workspaces. In complex projects, there may be the need for multiple pages or sections, in essence, applications within the larger app. Workspaces allow you to share common code (such as session management, custom UI components, and helper classes across these various subapplications). It also avoids the need to duplicate framework code (that is, the Ext JS source) across the subapps.
Note
The Sencha Cmd documentation has detailed documentation on workspaces at http://docs.sencha.com/cmd/5.x/workspaces.html.
Generating a workspace can be done with the following command:
sencha generate workspace ./my-workspace
This simply adds some configuration files for the workspace. The extra magic comes when you generate an application for this workspace:
sencha -sdk ~/<path-to-sdk>/ext generate app MyApp ./my-workspace/my-app
The key difference here is that the SDK will be held at the workspace root rather than the application...