at command for one-time jobs in Linux CLI - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the at command in Linux?

The at command schedules a one-time job to run at a specific time in the future.

beginner

How do you schedule a command to run at 3:30 PM today using at?

Run at 15:30, then enter the commands you want to run, and press Ctrl+D to save.

beginner

How can you list all pending jobs scheduled with at?

Use the command atq to see all pending at jobs for the current user.

beginner

How do you remove a scheduled at job?

Use atrm job_number where job_number is the ID from atq.

intermediate

What happens if you schedule an at job but the system is off at the scheduled time?

The job will not run because at does not run missed jobs after reboot.

Which command schedules a one-time job to run at 10:00 PM today?

A at 22:00

B cron 22:00

C batch 22:00

D schedule 22:00

The at command schedules one-time jobs; at 22:00 sets a job for 10 PM.

How do you view the list of pending at jobs?

A atq

B crontab -l

C jobs

D ls /etc/at.d

atq lists pending at jobs for the current user.

What key combination do you press to finish entering commands in an at session?

A Ctrl+C

B Ctrl+X

C Ctrl+D

D Ctrl+Z

Pressing Ctrl+D signals end-of-input to save the job.

If you want to cancel a scheduled at job, which command do you use?

A atstop job_number

B atcancel job_number

C atdel job_number

D atrm job_number

atrm job_number removes the scheduled at job.

Which of these is NOT true about the at command?

A It schedules one-time jobs.

B It runs missed jobs after reboot.

C It uses a simple time format like 'now + 1 hour'.

D It requires the <code>atd</code> daemon to be running.

at does NOT run missed jobs after reboot; jobs are lost if the system is off.

Explain how to schedule a one-time job using the at command and how to check if it is scheduled.

Think about the steps from scheduling to verifying.

Describe how to remove a scheduled job with the at command and why you might want to do this.

Focus on job management commands.