Oracle Data Pump (expdp) credentials via cron job

Question

I have Oracle 10.2 on Linux Red Hat Server. In additions to performing appropriate backups of my database I also have a cron job I use to performa full logical export using expdp every night to export user objects in the event that a singleobjects needs recovered. This is an extra safeguard for object recovery.
Currently I do my export (expdp) via a cron job run as the oracle software owner as a db user with db credentials specified. I would however like to change this script to essentially run as sys by doing something like "expdp / as sysdba... " However it appears doing so actually requires the password to be supplied and to run expdp as "expdp sys/password as sysdba".
does anyone have experience performng an expdp as sys without specifying the password... essentially being able to do "/ as sysdba"?
Hope that makes sense.
Thanks for any suggestions.

Answer 1

I appreciate all comments. At the expense of being long winded I did not get into all the details. But to be more clear I want to say
1. I am using a parfile as to hide the password from the ps command.
2. I also understand that doing it as sysdba is not recommended but i thought if I did so I could eliminate need for storing clear text password.
3. This system is on a seperate "air-gapped" (a.k.a "sneaker-net") from the outside world and is a better protected than if sitting somewhere near the internet.
4. Historically we have not been permitted to use OP$ accounts. This may be a legacy issue,and will (re-)investigate this as an option.
5. Just to be clear, I really do not want to do a full export as sysdba. In fact currently I am doing it as a user with EXP_FULL_DATABASE role. However, that requires password to be stored in file (parfile). The file has it in clear text which is still not optimal because System Admins could gain access to this password (Yes I know system admins could do larger damage, but we still need to protect the passwords).
I am going to look at calling the API directly, and OP$ if needed.
Thanks for the suggestions.