[Oracle DataBase Server 12.2 Installation on Oracle Linux 7.4]: Creating a Backup of the Created Database (Cold Backup)

$ rman target /

RMAN> shutdown immediate;
RMAN> startup mount;

RMAN> BACKUP DATABASE TAG "FULL_DATABASE_DATAFILES";
RMAN> BACKUP CURRENT CONTROLFILE TAG "FULL_DATABASE_CONTROLFILE";
RMAN> BACKUP SPFILE TAG "FULL_DATABASE_SPFILE";

RMAN> alter database open;

RMAN> quit

$ sqlplus / as sysdba

SQL> SELECT
    TO_CHAR(SPACE_USED, '999,999,999,999') AS "Used",
    TO_CHAR(SPACE_LIMIT - SPACE_USED + SPACE_RECLAIMABLE, '999,999,999,999')
       AS "Free",
    ROUND((SPACE_USED - SPACE_RECLAIMABLE)/SPACE_LIMIT * 100, 1)
       AS "Used %"
    FROM V$RECOVERY_FILE_DEST;

Used		 Free		      Used %
---------------- ---------------- ----------
     868,876,288   20,616,609,792	   4

SQL> quit