linux command -at scheduled task execution

#atq List the tasks at at#
atrm n Delete the task with task number n
# at time
1.at specific time
# at 18:00
at> echo "at executed" > /home/jack/at.out
at><EOT > #################### Ctrl + D
job 15 at Wed Dec 30 18:00:00 2015

HH:MM[am|pm] + number [minutes|hours |days|weeks]

The format of the specific time:
HH:MM [+ 3days] ### Execute
HH:MM tomorrow ### Tomorrow's HH:MM time

04:00 2009-03-17

ex> 04pm March 17

at 5pm
##
If you want to prevent a user from executing the at command, just add the username to
/etc/at.deny##