Using shutdown -h command to do a scheduled shutdown

If you wish to use the Linux command to remind users of scheduled maintenance and halts the system at 10:00am, you can use the command

# shutdown -h 10:00 "Scheduled Maintenance. Expected downtime at 10am"

Alternatively, you may wish to specify a relative downtime. If you wish to shutdown the system 20min when the command is executed

# shutdown -h +20 "We need to power down to do an emergency repair"