Different commands to shutdown or reboot

Here are list of commands that can be used to shutdown or reboot a system.
Note: All the commands require superuser privileges, hence use sudo for all of them.

1. Halt

The command halt will shutdown the system immediately.

2. Reboot

The command reboots the system

3. shutdown

The command can be used to shutdown as well as reboot the system by passing the correct options as given below

To shutdown immediately
sudo shutdown -h now

To shutdown after a time interval

sudo shutdown -h 15

This will shutdown the system after 15 minutes

To reboot :

shutdown -r now

To reboot after a time interval

shutdown -r 15

This will reboot the system after 15 seconds.

4. init

To reboot using init run

sudo init 6

This will reboot the system immediately.

5. poweroff

This will poweroff the system immediately just like the halt command