Examples of Using the AT Command

Listing Scheduled Jobs:

To list all scheduled jobs in the AT queue, you can use the `-l` option:

at -l

or

atq

This command will display a list of all pending jobs along with their job numbers.

Deleting a Scheduled Job:

If you need to remove a scheduled job from the queue, you can do so by specifying its job number with the -d option:

at -d 1

This command will delete the job with job number 1 from the AT queue.

Scheduling a Job for the Coming Monday

To schedule a job for the coming Monday at a time twenty minutes later than the current time, the syntax would be:

at Monday +20 minutes

• at: The command to schedule a one-time task.
• Monday: Specifies the next Monday as the starting point.
• +20 minutes: Adds 20 minutes to the specified starting point.

This command instructs the system to execute the specified job on the upcoming Monday, twenty minutes after the current time.

Scheduling a Job for a Specific Date and Time

To schedule a job to run at 1:45 on August 12, 2020, the command is:

at 1:45 081220

• 1:45: The time at which the command will be executed.
• 081220: The date in MMDDYY format, which stands for August 12, 2020

Here, the command specifies the exact date and time when the job should be executed, in the format of hour:minute monthdate.

Scheduling a Job for a Future Time

If you need to schedule a job to run at 3 PM four days from the current time, the command would be:

at 3pm + 4 days

• at 3pm: Specifies the time of day when the task should run, which is 3 PM.
• + 4 days: Adds four days to the current date to determine the execution date.

This command schedules the job to be executed at 3 PM, four days from the current time.

Scheduling a System Shutdown

To schedule a job to shutdown the system at 4:30 PM today, you can use the following command:

echo "shutdown -h now" | at -m 4:30

• echo "shutdown -h now": This part creates a command that shuts down the system immediately.
• |: The pipe operator (|) passes the output of the first command (echo "shutdown -h now") as input to the next command.
• at -m 4:30: This schedules the provided command to run at 4:30 (AM or PM). The -m flag tells at to send a mail to the user when the job is done (if mail is configured).

This command pipes the shutdown command to the AT command, specifying that the system should be shut down at 4:30 PM, and the user should receive an email notification when the job is completed.

Scheduling a Job for a Future Time Relative to Now

To schedule a job to run five hours from the current time, the command would be:

at now +5 hours

• at: This is the command used to schedule tasks for future execution.
• now +5 hours: This specifies the time at which the task should be executed.
  • now refers to the current time.
  • +5 hours adds 5 hours to the current time.

This command schedules the job to be executed five hours from the current time.

Different Method to delete job

at -r or atrm command is used to deletes job , here used to deletes job 11.

 at -r 11

• at is the command-line utility for scheduling one-time tasks.
• -r (or --remove) is an option to remove a scheduled job.
• 11 is the job number that you want to remove from the at queue.

or

atrm 11

Using a Shell Script File

Let’s say you want to create a script named backup.sh that performs a backup operation:

• Create the Script File: Open a text editor and create a file named backup.sh:

nano backup.sh

• Write the Script: Inside backup.sh, write your backup script.

For example:

#!/bin/bash
mkdir -p /backup
cp /path/to/important/files/* /backup
echo "Backup completed successfully!"

• Make the Script Executable: Make the script executable with the following command.

chmod +x backup.sh

• Schedule the Script with at Command: Now, you can schedule this script to run at a specific time using the at command

at 3pm + 4 days < backup.sh

This will schedule the backup.sh script to run at 3 PM four days from the current date.

In the world of Linux operating systems, there exists a powerful tool known as the “AT command.” The AT command provides users with the ability to schedule tasks to be executed at a later time, offering a convenient way to automate processes without manual intervention. Whether you need to run a script, execute a command, or perform a system task at a specific time, the AT command provides the flexibility to accomplish these tasks efficiently. In this article, we will delve into the details of the AT command in Linux, exploring its syntax, options, and practical examples.