Testing Oracle 10g installation on Red Hat Linux AS 4.0

One of my friend installed Oracle first time. After installation, he just wants to make sure everything is working fine so he called me. If you are installing oracle for Unix/Linux oses first time then it will confuse you. He wanted to know how to start oracle service and test it. He emailed me the following error:
ORA-27101: shared memory realm does not exist
ORA-01034: ORACLE not available

You need to add following line to oracle user’s .bash_profile file for testing purpose (once it is tested, you can give control to Oracle DBA) (login as a oracle user):
$ cd;vi .bash_profile
Append following lines:
export ORACLE_HOME=/home/oracle/oracle/product/10.2.0/db_1 export ORACLE_SID=orcl export PATH=$PATH:$ORACLE_HOME/bin
Save file. Just load the above settings:
$ . .bash_profile
Start oracle Net listing service:
$ lsnrctl start
ALTERNATIVELY use full path:
$ /home/oracle/oracle/product/10.2.0/db_1/bin/lsnrctl start
Start oracle database:
$ dbstart
ALTERNATIVELY, use full path:
$ /home/oracle/oracle/product/10.2.0/db_1/bin/dbstart
Connect to Oracle database with sqlplus client (test it with scott username):
$ sqlplus "scott/tiger" sql> select * from tab;
To shutdown Oracle database:
$ lsnrctl stop $ dbshut