Execute a command at a specified time

Problem

You want to run a command at a specified time, or at a certain amount of time from now.

Solution

Use at command to run arbitrary commands and scripts at a specified time.

There are 2 ways to run at: from user input or from a script

To run from user input

    at <time>
    ...type in the commands
    Ctrl-D

To run from a script

    at <time> -f <script>

To run a command immediately

    at now

To run a command at a specific time in the future

    # run this job at 10:00 Jan 10, 2015
    at 10:00 Jan 10 2015

    # run this job at midnight, noon, or teatime, respectively
    at midnight
    at noon
    at teatime

    # run this job at noon today or tomorrow
    at noon today
    at noon tomorrow

To run a command after an amount of time has elapsed from now, just add + to the time

    # run this job after 3 minutes
    at now + 3 minutes

    # run this job at 4pm 3 days from now
    at 4pm + 3 days

To list current jobs, use atq

    atq

To remove a job listed by atq, use atrm

    atrm 10

batch is similar to at, but it only executes command when system load levels permit, i.e., when the load average drops below 1.5.