以pfile或者spfile启动时show parameter pfile的不同结果

普通启动：
SQL> show parameter pfile

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
spfile                               string      /u01/app/oracle/product/11.2.0
                                                 /dbhome_1/dbs/spfilesingle1.or a

以pfile启动
SQL> startup nomount pfile=/home/oracle/pfile.ora
ORACLE instance started.

Total System Global Area  413372416 bytes
Fixed Size                  2253784 bytes
Variable Size             314575912 bytes
Database Buffers           92274688 bytes
Redo Buffers                4268032 bytes

SQL> alter database mount;

Database altered.

SQL> alter database open;

Database altered.

SQL>    show parameter pfile;

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
spfile                               string
SQL>

that"s the difference. 
普通启动：
SQL> show parameter pfile

NAME