Here is a list of some RMAN commands I frequently use:

1. To connect to RMAN without a repository:

rman target /

2. To crosscheck backups:

crosscheck backup;

3. To list expired backups:

list expired backup;

4. To delete expired backups:

delete expired backup;

5. To set a disk destination for backups:

CONFIGURE CHANNEL DEVICE TYPE DISK FORMAT   ‘E:backupDEV1%U’;

6. To include a maximum size of 2GB for backupset pieces:

CONFIGURE CHANNEL DEVICE TYPE DISK MAXPIECESIZE 2G FORMAT ‘E:backupDEV1%U’;

7. To execute a backup to the default location:

backup database;

8. To restore and recover datafile 30:

run {

restore datafile 30;

recover datafile 30;

}