Both the SPFILE and PFILE are located in directory:
$ORACLE_HOME/dbs
 
SHOW PARAMETER SPFILE;
SELECT name, value FROM v$parameter WHERE name = 'spfile';

-- Para criar o PFILE a partir do SPFILE:
CREATE PFILE='$PATH/PFILE_name' FROM SPFILE='$PATH/SPFILE_name';

-- Para criar o SPFILE a partir do PFILE:
CREATE SPFILE FROM PFILE;
CREATE SPFILE FROM PFILE='/u01/app/oracle/product/12.2.0/dbhome_1/dbs/init.ora'
CREATE SPFILE='/u01/app/oracle/product/12.2.0/dbhome_1/dbs/SPFILE.ora' FROM PFILE='/backup/init.ora'

STARTUP PFILE='/u01/app/oracle/product/12.2.0/dbhome_1/dbs/init.ora';
CREATE SPFILE FROM PFILE='/u01/admin/prod/PFILE/initprod.ora';

-- Necessário Reiniciar, A reinicialização utilizará o SPFILE criado.
SHUTDOWN IMMEDIATE;
STARTUP;

CREATE SPFILE='/u01/app/oracle/product/12.2.0/dbhome_1/dbs/initSID.ora' FROM PFILE='/storage/oracle/initnewdb.ora'
CREATE PFILE ='/u01/app/oracle/product/12.2.0/dbhome_1/dbs/initSID_BACKUP.ora' FROM SPFILE;
 
CREATE SPFILE FROM MEMORY;
CREATE PFILE FROM MEMORY; 

CREATE PFILE='/tmp/initSID.ora' FROM SPFILE;
CREATE PFILE='/tmp/initSID_memory.ora' FROM memory;
 
CREATE PFILE='/u01/app/oracle/product/VERSAO/db_1/dbs/init.ora' FROM memory;

CREATE PFILE ='/u01/app/oracle/product/VERSAO/db_1/dbs/PFILE.ora'     FROM SPFILE='/u01/app/oracle/product/VERSAO/db_1/dbs/SPFILESID.ora'; 
CREATE SPFILE='/u01/app/oracle/product/VERSAO/db_1/dbs/SPFILESID.ora' FROM PFILE ='/u01/app/oracle/product/VERSAO/db_1/dbs/init.ora';

-- Falha e a solução:
LRM-00109: could not open parameter file '/u01/app/oracle/product/11.2.0.4/db_1/dbs/init.ora';
STARTUP FORCE PFILE='/u01/app/oracle/product/11.2.0.4/db_1/dbs/init.ora';

--STARTUP database with PFILE or SPFILE
STARTUP [NOMOUNT | MOUNT | OPEN] PFILE='/backup/init.ora'

SQL> STARTUP NOMOUNT PFILE='/storage/oracle/initnewdb.ora';
STARTUP PFILE='';
STARTUP SPFILE='';
STARTUP SPFILE='/u01/app/oracle/product/12.2.0/dbhome_1/dbs/SPFILESID.ora';

restore SPFILE to PFILE '/tmp/initnewdb.ora' FROM '/tmp/SPFILESID.ora';

SET DBID 1234567890;
STARTUP FORCE NOMOUNT; 			# RMAN starts instance with dummy parameter file
RESTORE SPFILE FROM AUTOBACKUP; # restore a server parameter file
STARTUP FORCE; 					# restart instance with restored server parameter file