[Unix] Scheduling jobs using at command in Unix

[How To] Schedule jobs in Unix using at command

At command read commands from standard input or a specified file which are to be executed at a later point time. You may specify noon, teatime, midnight, AM, PM, exact time or time units to as arguments with the job to be run.

For example, to run a job at 4pm three days from now, you would do at 4pm + 3 days.

Usage:
$ at [time]
at> [jobname]
at> cntrl+d

The above command will execute the [jobname] at [time]. cntrl+D stands of EOT (end of transmission).

Example:
We will see a simple example to create a file named myfile with the text "hi" at a later point of time. The various time scheduling options available (not the complete list!) is as below

$ at noon
at> echo "hi" > myflie
at >

Once you press cntrl+d, you will recive and the beliow mesage from the shell.
Commands will be executed using /bin/ksh
job 1374224400.a at Fri Jul 19 12:00 PM 2013

at comand example
Note: In all cases of specifying a time only, the command will run at that time today if the specified time is in the future, or tomorrow otherwise.  For example if you specify 3:00 PM and it is currently only 1:00 PM, the at job will run in two hours from now.  But if it is currently 3:30 PM, the job will run tomorrow at 3 PM.

$ at midnight
at> echo "hi" > myflie
at >

The above command will create the file myfile at 12:00 AM today.

$ at next week
at> echo "hi" > myflie
at >

The above command will create the file myfile next week, at the same time as it was when the above command was executed.

$ at 9:00 AM
at> echo "hi" > myflie
at >

The above command will create the file myfile at 09:00 AM today.

$ at now + 30 minutes 
at> echo "hi" > myflie
at >

The above command will create the file myfile at 30 minutes from now.

$ at now + 3 weeks 
at> echo "hi" > myflie
at >

The above command will create the file myfile at 3 weeks from now.

$ at 2:30 PM 21.9.14
at> echo "hi" > myflie
at >

The above command will create the file myfile on 21st September at 02:30 PM.