GNU Grub allows you to have several operating system on system and user can select one to start. Grub allows you to boot different kernels, operating system, floppy / cd boot and network boot. Dedoimedo.com has published article about how to setup and configure GRUB bootloader with multiple operating systems. This article is a compilation of sources and examples that will help you learn about GRUB. New Linux users will probably find the notion of spending hours searching for relevant pieces of information (especially if their PC won’t boot) somewhat frustrating. The goal of this guide is to help provide simple and quick solutions to most common problems regarding multi-boot setups and installation of Linux operating systems:
With FreeBSD version 5.4 and above the booting procedure is slightly changed. The older version of FreeBSD uses the boot -s option at Ok prompt. However, with FreeBSD version FreeBSD 5.4+ you don’t have to type any commands. Here is the procedure to boot FreeBSD into a single user mode to reset root password.