In Linux you can list the contents of a users crontab from root by issuing the below command:
[root@server ~]#crontab -u username -l
How do you list crontabs for all of the users on your Linux server? The easiest way is to list the contents of /var/spool/cron which will provide you a list of all of the users that have cron entries. Then if you need the specific details of a users cron entries you can use the command above and replace username with the username in question to see the details.