There may be occasions where you, as the administrator of a machine, may want to see what cron entries your users have. Maybe you have slow downs at a particular time every day, and want to see who’s running what.
All crontab’s, for all users, are stored in /var/spool/cron/crontabs on Debian and Ubuntu, as plain text files. So, as root, you will be able to cat any of the files in there – they are stored as the username, so:
/var/spool/cron/crontabs/daz
… would be a user called “daz” for example.
In CentOS, the path is slightly different – there is no crontabs directory, so it’s simply:
/var/spool/cron/
You can also find out an individual users’ crontab by issuing (as root);
crontab -l -u username
This will show you that users crontab. Of course, if you want to edit it, you can by doing:
crontab -e -u username