Oracle Listener Error on Red hat 5

Hello everybody, the reason why im posting this thread is because i've installed an oracle test database on RHEL 5, on a localhost (Since it is for test)... the thing is, after i have installed the DB it works just fine, but after i re start it, i get the following errors when i want to go into the sqlplus....

[oracle@localhost ~]$ sqlplus system

SQL*Plus: Release 10.2.0.1.0 - Production on Tue Nov 22 22:28:10 2011

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

Enter password: 
ERROR:
ORA-01034: ORACLE not available
ORA-27101: shared memory realm does not exist
Linux Error: 2: No such file or directory

:wall:
i already checked my listener.ora and i get this...

[oracle@localhost admin]$ more listener.ora
# listener.ora Network Configuration File: /u01/app/oracle/product/10.2.0/db_1/n
etwork/admin/listener.ora
# Generated by Oracle configuration tools.

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = PLSExtProc)
      (ORACLE_HOME = /u01/app/oracle/product/10.2.0/db_1)
      (PROGRAM = extproc)
    )
  )

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
      (ADDRESS = (PROTOCOL = TCP)(HOST = localhost.localdomain)(PORT = 1521))
    )
  )

and sqlnet.ora gives me this...

[oracle@localhost admin]$ more sqlnet.ora
# sqlnet.ora Network Configuration File: /u01/app/oracle/product/10.2.0/db_1/net
work/admin/sqlnet.ora
# Generated by Oracle configuration tools.

NAMES.DIRECTORY_PATH= (TNSNAMES, EZCONNECT)

tnsnames.ora goes like...

[oracle@localhost admin]$ more tnsnames.ora
# tnsnames.ora Network Configuration File: /u01/app/oracle/product/10.2.0/db_1/n
etwork/admin/tnsnames.ora
# Generated by Oracle configuration tools.

PRUEBADB =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = localhost.localdomain)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = PRUEBADB)
    )
  )

EXTPROC_CONNECTION_DATA =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
    )
    (CONNECT_DATA =
      (SID = PLSExtProc)
      (PRESENTATION = RO)
    )
  )

I've searched over the web and i have found nothing... And i already thank you for your time. Hope you can help me.

You need to first check if your oracle env setting is correct.

what are the value of oracle env variables

ORACLE_SID and ORACLE_HOME

The values are...

[oracle@localhost~]$ echo $ORACLE_HOME

/u01/app/oracle/product/10.2.0/db_1

and ...

[oracle@localhost~]$ echo $ORACLE_SID
TESTDB

The Oracle System ID (SID) is used to uniquely identify a particular database on a system.

your ORACLE_SID should be the

PRUEBADB

Ok, i already re installed the DB and im having the same problem, and this time my ORACLE_SID value is PRUEBADB. Any thoughts???

are you able to connect a sysdba

 
sqlplus '/ as sysdba'