Prerequisites
Switch on a physical server or a virtual machine (in this case, type: # virsh start vm).
Connect to the console.
Basic Management
To reboot the system, choose one command among these:
# reboot # systemctl reboot # shutdown -r now # init 6 # telinit 6
To shutdown the system, choose one command among these:
# halt # systemctl halt # shutdown -h now # init 0 # telinit 0
To switch off the system, choose one command among these:
# poweroff # systemctl poweroff
Advanced Management
To suspend the system, type:
# systemctl suspend
To put the system into hibernation, type:
# systemctl hibernate
To put the system into hibernation and suspend it, type:
# systemctl hybrid-sleep
Additional Resources
Bob Cromwell provides some very interesting pages about Linux kernel details and the Linux boot process.