In Linux, the init 6 command gracefully reboots the system running all the K* shutdown scripts first, before rebooting. The reboot command does a very quick reboot. It doesn’t execute any kill scripts, but just unmounts filesystems and restarts the system. The reboot command is more forceful.
Source: http://www.vreference.com/2009/09/23/reboot-is-not-the-same-as-init-6/
This seems to be true for Unix systems as Solaris, but I have always seen the following 3 commands as synonyms, as they all seem to shut down the services before unmounting the filesystems and restart the server:
shutdown -r now
reboot
init 6
Can somebody tell the differences between these commands?
There is no difference in them. Internally they do exactly the same thing: