Gnome Shell uses the tracker utility to log things like that. From the documentation:
Data & Logging
The databases are kept in
$HOME/.cache/tracker. The user's data backup is kept in
If Tracker is configured to have the logging verbosity (set in GSettings or each .cfg file for each main component) set to a value higher than 0, then logs are generated and will usually be sent to the system journal or syslog. If the
TRACKER_USE_LOG_FILES environment variable is set for a Tracker daemon it will cause logs to be written to
$HOME/.local/share/tracker in addition.
I'd like to access the "starred" attributions from outside nautilus, that's why.
You can not. tracker-writeback is used for writing to the database but as the man page states:
tracker-writeback — Used to write metadata set in Tracker back to physical files.
tracker-writeback is not supposed to be run by the user since it is started by its
.desktop file when the user logs in. It can also be started manually of course for debugging purposes. You can not run more than one instance of this at the same time.
For viewing data:
tracker-extract — Extract metadata from a file.
tracker extract reads the file provided and extracts any metadata it can from this file, then displays the metadata on standard output.
The metadata is displayed as a SPARQL update command, that can be run against a SPARQL endpoint to update its copy of the metadata.
The actual extraction is done by a separate process. This is done to isolate the calling process from any memory leaks or crashes in the libraries Tracker uses to extract metadata.
For more information see the libtracker-extract reference documentation.
There are no command line tools provided for inserting metadata into the database back-end. It is all tied into gnome shell.