Shutdown (shutdown, restart, and logout of the system)

shutdown -h now shuts down the system (1) 
init 0 shuts down the system (2) 
telinit 0 shuts down the system (3) 
shutdown -h hours:minutes & shuts down the system at the scheduled time 
shutdown -c cancels the  system shutdown at the scheduled time
shutdown -r now restarts ( 1) 
reboot reboot (2) 
logout logout