Job automation quest for solaris adminstration

1. Find the difference between at and cron.
2. Find the daemon for the corn.
3. Restrict a particular user to use at utility.
4. Create an at job which generates an mail after finishing the job.
5. Try out all options with at command.
6. Verify that crontab file exists or not.
7. Deny an user to use the crontab Utility.
8. Try to edit the same user name in the allow file and deny file and check which file is giving the preference.
9. Write a cron job to take backup ever Thursday night at 11.00 p.m.
10. Write a cron job which gives information of how many users are logins in every 1 hour.