Stop the system 15 minutes from now.
Use a standard command that can notify logged-in users.
Which command is appropriate?
shutdown accepts +minutes for a relative time. A scheduled shutdown can commonly be canceled with shutdown -c.
Detailed explanation
halt +15Incorrect. halt does not use this standard relative scheduling syntax.
reboot 15Incorrect. reboot is not the scheduled shutdown command here.
sleep 15; poweroffIncorrect. A shell sleep is not the managed, notifying shutdown workflow.
shutdown -h +15Correct. shutdown -h +15 schedules a halt in 15 minutes.
Try it yourself
An example you can run in a temporary verification environment.
shutdown --helpExpected result
+m形式の時刻指定。予約は実行しないKey points
- +15 means 15 minutes
- Scheduled shutdown
- User notification
Notes
- Environment: systemd systemctl互換shutdown
- Use a disposable VM or test account when validating installation and SSH behavior.
- Exact command output can vary slightly by distribution and OpenSSH version.
Foundation review
Identify the scope
A reboot command, a shell sleep, and an immediate halt do not provide the same notification and scheduling behavior.
Check the side effect
Inspect the pending shutdown state and communicate the scheduled time to logged-in users.