Crontab Cheat Sheet
Under Ubuntu or debian, you can view crontab by
/var/spool/cron/crontabs/ and then a file for each user is in there.
But hell hath no fury, you will see this:
# DO NOT EDIT THIS FILE – edit the master and reinstall.
Now what gives?
To edit the file:
sudo su - other_user
How to use sudo and su to elevate yourself to root and then to another user