[Oracle DataBase Server 12.2 Installation on Oracle Linux 7.4]: Final Backup (Hot Backup):

$ mkdir -p /u02/oracle/oradata/12.2/${ORACLE_SID}/scripts

$ cd /u02/oracle/oradata/12.2/${ORACLE_SID}/scripts

$ vi rmanscript.rman

RUN {
    CONFIGURE DEVICE TYPE DISK BACKUP TYPE TO COMPRESSED BACKUPSET;
    BACKUP FULL DATABASE TAG "FULL_DATABASE" PLUS ARCHIVELOG TAG "FULL_DATABASE_ARCHIVELOGS";
    BACKUP CURRENT CONTROLFILE TAG "FULL_DATABASE_CONTROLFILE";
    BACKUP SPFILE TAG "FULL_DATABASE_SPFILE";
}

Check the syntax of the created script file

$ rman CHECKSYNTAX @rmanscript.rman

Run the backup script

$ rman target / @rmanscript.rman

View the list of backups

RMAN> rman target /

RMAN> list backup of database summary;

With the following command, I specify that all backups except the last one should be marked as obsolete.

RMAN> CONFIGURE RETENTION POLICY TO REDUNDANCY 1;

Now I tell RMAN to delete obsolete backups (without confirmation).

RMAN> delete noprompt obsolete;

RMAN> list backup of database summary;

List of Backups
===============
Key     TY LV S Device Type Completion Time     #Pieces #Copies Compressed Tag
------- -- -- - ----------- ------------------- ------- ------- ---------- ---
1       B  F  A DISK        14/08/2017 14:31:28 1       1       NO         FULL_DATABASE_DATAFILES
8       B  F  A DISK        14/08/2017 15:15:39 1       1       YES        FULL_DATABASE

RMAN>  quit