being able to run SQL using scripts through process scheduler without hardcoding userid/password

I would like to run scripts via the process scheduler.  These scripts should call SQL.

The only way I can think to do this is to have this inside the script:

SQLPLUS username/password@database test.sql

Is there a way for me to not have to hardcode the username and password into the scripts that I am using?

These scripts are running on Unix

We are on HRMS 9.1 PeopleTools 8.51

Thanks!