For those who may find it helpful, here's a problem I ran into along with the solution.
When a Korn shell script using Oracle 10gR2 client's sqlplus was run manually at the command prompt, the script successfully used an Oracle Wallet to log in and run an SQL script.
However, when the same ksh script was run with a cron job, I would get the following error:
"ORA-12534: TNS:operation not supported".