Create Spool file from RMAN command prompt

RMAN> spool log to "/tmp/rman.log"
RMAN> list backup of database;
RMAN> spool off;
RMAN> host 'ls -ltr /tmp/rman.log'
2> ;
-rw-rw-r-- 1 oracle oinstall 1111 May 14 08:08 /tmp/rman.log