Embedded Files
Concept
Concept
at only run scheduled task one-time only.
Time Settings
Time Settings
24-Hour Format
at [Time in 24-Hour Format]
Example: at 14:30
Schedules for 2:30 PM today, or tomorrow if 14:30 has already passed
12-Hour Format
at [Time in 12-Hour Format]
Example: at 2:30 PM
Specific Date & Time
at [Time in 12 or 24-Hour Format] [Date]
[Date] format could be
MMM DD at 2:00 PM Sep 17
MM/DD/YY at 14:00 09/17/26
YYYY-MM-DD at 2:00 PM 2026-09-17
Offset from now
at now + [Number] [ minutes/hours/days ]
Example: at now + 30 minutes
Time Aliases
at [Alias]
Time alias such as now, midnight (12:00 AM), noon (12:00 PM), teatime (4:00 PM)
Example: at midnight
Tutorial
Tutorial
Verify at command can be use or not
systemctl status atd
If the atd service not active, start the service : systemctl start atd
Run at job
Run at command at specific time
at [Time settings]
Example: at 4:30 PM
Add command to create file (or other command) when time reach
touch /tmp/[File name]
Example: touch /tmp/testing
Press Enter --> Ctrl+D to stop edit command
List all active jobs of at command
atq
Wait till time passed
date
List all file under the directory and find the file
ls /tmp
Cleanup
rm -rf /tmp/[File name]
Example: rm -rf /tmp/testing
Cancel at job
Run at command at specific time
at [Time settings]
Example: at 4:30 PM
Add command to create file (or other command) when time reach
touch /tmp/[File name]
Example: touch /tmp/testing
Press Enter --> Ctrl+D to stop edit command
List all active jobs of at command, record the [Job index]
atq
Delete the job
atrm [Job index]
Example: atrm 3
Verify job is deleted
atq
Result
student@localhost:~$ at 4:30 PM
warning: commands will be executed using /bin/sh
at Thu Sep 17 16:30:00 2026
at> touch /tmp/testing
at> <EOT>
job 2 at Thu Sep 17 16:30:00 2026
student@localhost:~$ atq
2 Thu Sep 17 16:30:00 2026 a student
student@localhost:~$ date
Thu Sep 17 04:31:19 PM +08 2026
student@localhost:~$ ls /tmp
systemd-private-c9b83bc258274206b135dfb4f68b70ae-chronyd.service-TArwNy
systemd-private-c9b83bc258274206b135dfb4f68b70ae-colord.service-JPVfK1
systemd-private-c9b83bc258274206b135dfb4f68b70ae-dbus-broker.service-hHcxlm
systemd-private-c9b83bc258274206b135dfb4f68b70ae-fwupd.service-OowZz6
systemd-private-c9b83bc258274206b135dfb4f68b70ae-irqbalance.service-XQvtK6
systemd-private-c9b83bc258274206b135dfb4f68b70ae-ModemManager.service-tWlfEp
systemd-private-c9b83bc258274206b135dfb4f68b70ae-polkit.service-2kIYtF
systemd-private-c9b83bc258274206b135dfb4f68b70ae-rtkit-daemon.service-CVB9ju
systemd-private-c9b83bc258274206b135dfb4f68b70ae-switcheroo-control.service-WhUnbv
systemd-private-c9b83bc258274206b135dfb4f68b70ae-systemd-logind.service-J0hWMv
systemd-private-c9b83bc258274206b135dfb4f68b70ae-upower.service-RHZair
testing
student@localhost:~$ rm -rf /tmp/testing
student@localhost:~$ at 4:30 PM
warning: commands will be executed using /bin/sh
at Fri Sep 18 16:30:00 2026
at> touch /tmp/testing
at> <EOT>
job 3 at Fri Sep 18 16:30:00 2026
student@localhost:~$ atq
3 Fri Sep 18 16:30:00 2026 a student
student@localhost:~$ atrm 3
student@localhost:~$ atq
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