The proper way to shutdown is to use the shutdown command.

For Example:

sudo shutdown -P now

shutdown [OPTION]… TIME [MESSAGE]

-h Requests that the system be either halted or powered off after it has been brought down, with the choice as to which left up to the system.

-H Requests that the system be halted after it has been brought down.

-P Requests that the system be powered off after it has been brought down.