A brief discussion on the environment variable Oracle_sid

[Email protected] ~]$ export oracle_sid=12323
[Email protected] ~]$!sql
Sqlplus/as SYSDBA

Sql*plus:release 10.2.0.1.0-production on Thu Nov 6 02:24:04 2014

Copyright (c) 1982, 2005, Oracle. All rights reserved.

Connected to an idle instance.


Sql> Startup
Ora-01078:failure in processing system parameters
Lrm-00109:could not open parameter file '/u02/app/oracle/product/10.2.0/db_1/dbs/init12323.ora '

Sql>

First of all, set a random oracle_sid, then log in to Sqlplus and then knock "Startup", when Oracle will ORACLE_SID according to the environment variables to $ORACLE _home/dbs to install the order

spfile12323.ora--"

pfile.ora--"

init12323.ora--"

init.ora--"

To find the initialization parameters file for Oracle. Since it is the initialization parameter file, it is of course to configure some things for Oracle-"shared memory, background process

This information can be seen when a normal instance (instance) is initialized:

1 ". Shared Memory segment:

[Email protected] ~]$ ipcs-a


------Shared Memory Segments--------
Key shmid owner perms bytes nattch Status
0x00000000 2785281 Root 644 80 2
0x00000000 2818050 Root 644 16384 2
0x00000000 2850819 Root 644 280 2
0xa1728964 3244037 oracle10g 640 216006656---Here oracle10g is a user of Oracle software


------Semaphore Arrays--------
Key Semid owner Perms Nsems
0X17EE0B04 1441793 oracle10g 640 154


------Message Queues--------
Key Msqid owner perms used-bytes messages

When you specify a pfile, this is the time to start an instance:

[Email protected] dbs]$ ipcs-a


------Shared Memory Segments--------
Key shmid owner perms bytes nattch Status
0x00000000 2785281 Root 644 80 2
0x00000000 2818050 Root 644 16384 2
0x00000000 2850819 Root 644 280 2
0xa1728964 3244037 oracle10g 640 216006656 20
0xb4c20568 3276806 oracle10g 640 169869312 10


------Semaphore Arrays--------
Key Semid owner Perms Nsems
0X17EE0B04 1441793 oracle10g 640 154
0x65dc2878 1572866 oracle10g 640 44


------Message Queues--------
Key Msqid owner perms used-bytes messages


[Email protected] dbs]$ Ps-ef|grep Smon
54322 17981 1 0 Nov05? 00:00:02 ora_smon_ora10g
54322 22649 1 0 02:41? 00:00:00 ora_smon_12323
54322 22660 22299 0 02:42 pts/3 00:00:00 grep smon
[Email protected] dbs]$

Again, the Oracle_sid and Oracle's db_name are not the same; Oralce_sid is simply to uniquely identify an instance of Oracle (instance)!

A brief discussion on the environment variable Oracle_sid