If you have a dual (or more) boot system you already know what a test of patience rebooting from one OS to another is – issue a reboot, wait for bootloader menu, select, enter… Definitely it would be simpler if all of these can be done with a single command or click. This can be done both on Windows and Linux very easily so that the next time you reboot you do not need to sit in front of the system to boot into the correct OS. Quite helpful on headless servers.
$ sudo grub-reboot MENU_ENTRY
where, MENU_ENTRY is from GRUB menu file (e.g., /boot/grub/grub.cfg)
iReboot does it for you.