Another difference between a 'crontab'-job and an 'at'-job.

When you issue a job using at, the unix-environment is automatically put in the job. eg. when you have set your oracle environment, and you start a job using at, automaticly you have the right oracle settings.

When you issue a job using crontab, you have to set the environment in the script. That's why I always begin a crontab job with
. /etc/profile
. $HOME/.profile

Regards
Gert