oracle home

If you set everything up properly and have populated your oratab file then edit your .profile:
vi ~/.profile

add the following:

export ORACLE_SID=SOME_SID
ORAENV_ASK=NO
. oraenv

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Replace SOME_SID to a correct ORALCE_SID that you have.

If you don't have the oratab set up properly in your .profile:
export ORACLE_HOME=/oracle/app/oracle/product/11.2.0./db

If you have only one Oracle home, one solution is to hard code the value into the ORACLE_HOME variable at the start of your session.  On linux/unix, for example, you can add to your profile:

export ORACLE_HOME=/oracle/app/oracle/product/11.2.0./db

dvz,

That's a little long for you to catch me typing...

[oracle@server1 ~]$ vi~./profile
bash: vi~./profile: No such file or directory
[oracle@server1 ~]$

Based on the message you received your login shell seems to be bash.  In that case you should modify ~/.bash_profile or ~/.bashrc not ~/.profile    Unfortunately different shells use different profile scripts.

slight, regrets, your answer wasn't there when I posted.  I can't explain the lag.

yes