0 */1 * * * foobar /home/foobar/foobar.sh
Apparently, there are three ways to run a cron job as specific user in Ubuntu.
1. Edit /etc/crontab and append above line to the file. Not recommended as it may lost due to package update or upgrade.
2. Create a file call foobar and put the above line in /etc/cron.d. Recommended as all users cron jobs are located in one location.
3. Create a crontab using that user. Workable but not located in centralized location like in (2).
$ sudo crontab -u foobar -e