What is the outcome of the SHUTDOWN ABORT command?

This describes a normal or transactional shutdown, where pending transactions are either committed or rolled back, and the database is properly closed.

The SHUTDOWN ABORT command terminates the instance processes immediately without writing dirty buffers from the buffer cache to data files or unwritten redo information to the redo log files. This abrupt termination leaves the database in an inconsistent state, necessitating instance recovery when the database is subsequently started.

This describes a transactional shutdown, where uncommitted transactions are rolled back before the instance shuts down.

While instance recovery is required at the next startup after a SHUTDOWN ABORT, it is an automatic process performed by the instance itself, not explicitly requested by the DBA.