CRON BAD ULIMIT ATTEMPTING BATCH ORACLE JOBS, SCO UNIX

Can anyone offer some suggestions on resolving our inability to make use of Unix batch facilities, ie, at, batch, etc, with Oracle scripts? We get a message from cron sent to mail saying "sh: Bad ulimit".

For instance, when the following command is submitted to the batch queue for execution at a future time, when that time arrives the job instantly fails:- at now + 1 minute sqlplus -s user/pswd _at_test.sql &

Placing the sqlplus command in a file, ie, at now + 1 minute < cmdfile gives the same result.

ulimit is 2113674 so there should not be a problem. Any non-oracle job submitted runs successfully at the appointed time.

Could it be an installation problem? Or something relating to the environment? Any advice will be gratefully received.

Software is as follows: SCO UNIX 3.4.2

                        Oracle Server 7.0.12
                        SQL/Plus 3.1.1
                        PL/SQL 2.0.14

-- 
Alan Muster