RMAN: restore the spfile

$sqlplus /nolog;
SQL>connect / as sysdba;
SQL>startup nomount;
SQL>exit;
$rman target / nocatalog
RMAN>set dbid=147749264
RMAN>run
{
allocate channel d1 type disk;
set CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO ‘$ORACLE_BASE/oradata/rman_backup/control%F’;
Restore spfile from autobackup;
Release channel d1;
}
Here is the error info: RMAN-06564: rman must use the t0 clause when the instance is started with spfile
This error info implies that you were using default SPFILE [...]

RMAN: can’t open target

$rman target / catalog
rman: can’t open target % ERROR INFO
Because there is another rman file in the system (use which to see the file location as follows). The ORACLE rman is in $ORACLE_HOME/bin.
$which rman
/usr/X11R6/bin/rman
Two ways to solve this problem:
1) Put $ORACLE_HOME/bin at the very beginning of $PATH in your environment
2) run [...]