As a root I run three dd processes in the background

dd if=/dev/urandom of=/dev/null &

dd if=/dev/urandom of=/dev/null &

dd if=/dev/urandom of=/dev/null &

As a root I edit a crontab and put a job to kill all dd processes that were run by root every minute

crontab -e 



* * * * * pkill -u root dd 

But when I use top to monitor processes the dd processes don't get killed. Why ?

Messages from /var/log/syslog :

Dec  9 12:33:01 champion CRON[3395]: Authentication failure

Dec  9 12:33:29 champion crontab[3383]: (root) END EDIT (root)

Dec  9 12:34:01 champion cron[1432]: Authentication failure

Dec  9 12:34:01 champion CRON[3398]: Authentication failure

Tried these suggestions but it didn't help :

1. Invoke the crontab with :

   
   

   crontab -e -u root

   
   



2. Make sure that you have an empty line at the end of the cronjob file, meaning that every line ends with a newline.