Linux - How to shutdown or reboot

To reboot.

[root@myserver]# reboot or [root@myserver]# shutdown -r now or [root@myserver]# init 6

To shutdown the Operating System.
By default shutdown command will bring the Operating System to runlevel 1

[root@myserver]# shutdown

To shutdown the Operating System and poweroff.

[root@myserver]# shutdown -h now

To cancel shutdown.

[root@myserver]# shutdown -c