I started a cron job on a cluster super computer. I am just a usual user over there and has no root power. The cron job was set by using "crontab -e". It excecutes a perl command every 20 minutes. I could use crontab -l or crontab -r to list or remove the cron job. However, I just found that I could not see the cron job anymore: "crontab -l" or "crontab -e" shows that I have no cron jobs setup. Then I noticed the old cron job is still running: it excecutes the perl command every 20 minutes. The perl command runs fast and there is nothing hanging over. Now, the "crontab -r" does not remove the cron job at all. I can still add new crontab jobs by using "crontab -e", but the old cron job seems to be out of my control.

How can I stop the cron job like this? I know I can change the conrtol file to make the old cron job do nothing, but I still prefer to get rid of it. Any thought on this? Thanks.