Help need Connecting to Oracle DB from Unix

I have a table called CLARIFICATION in one of my schema in Oracle Data Base. I have to connect to oracle Data Base from Unix and compare the one of the column(Exec_Date) in CLARIFICATION table with Sysdate.If Exec_Date = Sysdate go head and run rest of the script otherwise exit out with out throwing any errors.

Can you please help me how do I do it in Unix

Thanks in Advance

We dont what OS you are using nor oracle version nor do we know if oracle is on the same box or elsewhere...

Oracle is on the same box. We are using Oracle 9i.