Are you referring to retrieving all of the saved aggregation pipelines?
In the current versions of Compass (1.20 and older), saved aggregation pipelines are stored in an IndexedDB format that is embedded in the application preferences. This is only intended for use in the application, so accessing the full source of saved aggregations isn’t a current end user feature: you would have to load and export pipelines individually via the user interface.
However, a few users have requested easier access/sharing of pipelines, so future versions of Compass should load saved pipelines from disk instead. The improvement for this is currently in code review: COMPASS-3884: Migrate saved aggregations from IndexedDB to the filesystem.
Regards,
Stennie