Explanation:
After restoring the entire database, you must MOUNT the database to perform an incomplete recovery using RMAN. To mount the database using RMAN, you must execute the following command:

 RMAN> STARTUP MOUNT 

Or if the database is already in the NOMOUNT state, then you must execute the following command:

 RMAN> MOUNT DATABASE 

Reference:
Oracle 9i Net Services Administrator’s Guide
Oracle 9i Net Services Reference Guide
Oracle 9i Recovery Manager Reference
Oracle 9i Backup and Recovery Concepts

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