[Oracle DataBase Server 12.1 installation on Oracle Linux 6.7]: Create a 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 %
---------------- ---------------- ----------
     754,827,264   20,730,118,144	 3.5

SQL> quit