How to start/stop DB instance of Oracle under Linux

All below actions should be executed with "oracle" user account

1. Check the status of listener

$ lsnrctl status





2. If the listener isn't be started, start it

$ lsnrctl start





3. Set the "ORACLE_SID" environment to the DB instance's SID which you want to start, for example

$ export ORACLE_SID=PC855





4. Start sqlplus and start the DB instance

$ sqlplus "/as sysdba"

SQL> startup





5. If you want to stop the DB instance

$ sqlplus "/as sysdba"

SQL> shutdown immediate





6. Check the DB instance status again

$ lsnrctl status

Notes:

1. Make sure the listener be started before starting the DB instance

2. Make sure the ORACLE_SID environment has been set correctly

3. To configure the listener

$ netca

or

$ netmgr

4. To configure the DB instance

$ dbca