Oracle RMAN Configuration – Run Block Without Saving

If logging with RMAN, you'd have to set the filename yourself - there's no wildcard. But there is an APPEND option.

spool log to 'my_log_file' append

Similarly, invoking RMAN with the APPEND option causes it to append to any log file specified.

Our backup scripts do the log maintenance at the OS level:

export LOGPREFIX=$ORACLE_ADMIN/$ORACLE_SID/rman/log/my_backup_script
export MYLOG=${LOGPREFIX}.$$   # add the pid to the log file name
rman log=${MYLOG} append <<EOF
... various RMAN commands
EOF

#Perform error checking and notification
fgrep -i RMAN- ${MYLOG}
if [ $? -eq 0 ]
then # we had a failure - email me
   mail -s "$0 : failure for `date +%m/%d/%y`" me@myself_and_i.com < ${MYLOG}
fi
# add the incremental log to the permanent log
cat ${MYLOG} >> ${LOGPREFIX}.log
# clean up the incremental log
/bin/rm -f ${MYLOG}

I cannot say for sure why RMAN behaves in this way, but as a workaround you can edit the resulting script within the same workflow in EM before the job is created:

 ALLOCATE CHANNEL disk1 DEVICE TYPE DISK FORMAT '/disk1/%d_backups/%U';

This will ensure the backups are placed in the destination you specified regardless of RMAN settings in control file saved with CONFIGURE command.