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at – Execute a Task at a Specified Time

The at command in Linux is used to schedule a task to run at a specific time. This can be useful for automating tasks that need to be performed at a certain time or for running tasks during off-peak hours.

Overview

The at command is used to schedule a task to run at a specific time. The syntax for the command is as follows:

at [-f filename] [-m] [-q queue] [-t time] [-v] [time]

The time argument specifies when the task should be run. This argument can be specified in a variety of formats, including absolute times, relative times, and even natural language.

For example, to schedule a task to run at 2:30 PM on June 1st, you would use the following command:

at 2:30pm June 1

Once the at command is executed, you will be prompted to enter the command that you want to run at the specified time. For example, if you wanted to schedule a backup script to run at 2:30 PM on June 1st, you would use the following commands:

at 2:30pm June 1
at> /path/to/backup/script.sh
at> <EOT>

The at command will then schedule the task to run at the specified time. You can view a list of scheduled tasks by using the atq command, and you can remove a scheduled task by using the atrm command followed by the job number.

Options

The following table lists the available options for the at command:

Option Description
-f Specifies a filename to read the command from
-m Sends an email to the user when the task is complete
-q Specifies the queue that the task should be added to
-t Specifies the time that the task should be run
-v Verbose output

Troubleshooting Tips

  • If a task does not run at the scheduled time, check the system logs for any error messages related to the at command.
  • If the at command is not available on your system, you may need to install the at package using your system’s package manager.

Notes

  • The at command requires the atd daemon to be running on your system in order to function properly.
  • The at command is not available on all Linux distributions by default, so you may need to install it manually.

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