getting started your Oracle environment

check_oracle_env.sh

echo $ORACLE_HOME
echo $ORACLE_SID

start_lsnr.sh

lsnrctl start

start_oracle.sh

sqlplus "/ as sysdba"
# then under the sqlplus console:
> startup

test_connection.sh

sqlplus username/password@//hostname:PORT/SID
# if everything is fine, your should connect to the database, 
# and the following SQL query will return 1;
> select 1 from dual;