To boot a system, or to boot it to specific run levels, the commands to use depend on the system's platform. On SPARC systems, you must be on the ok prompt to issue boot commands. Also, the boot process might prompt you for a password.
This example boots a system to the default multiuser state.
ON SPARC systems:
$ init 0 ok boot
On x86 platforms:
$ reboot
This example boots a system to a single user state.
On SPARC systems:
$ init 0 ok boot -s
On x86 platforms:
$ reboot -p
The –p option displays the GRUB menu at boot time.
From the GRUB menu, select the boot entry that you want to modify, then type e to edit that entry.
Add –s at the end of the $multiboot line.
Press the appropriate keys to continue booting.