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Booting Linux

Linux Loader (lilo)

lilo prompts you after boot up to choose the OS and
you can give certain boot options to the kernel.

/etc/lilo.conf: Configuration file, allows booting different Linux version or an other OS like Windows.
Run lilo once after changing the config file.

GRand Unified Bootloader (grub)

grub understands filesystems and kernel executable formats, so you can load an arbitrary operating system just by specifying the kernel file name and the drive (and the partition) where the kernel resides (without recording the physical position of your kernel on the disk as with lilo). /boot/grub/menu.lst: Configuration file.

Boot Process and init -- The First Process

  1. Unpack kernel into memory
  2. kernel is executed, it begins to initializing hardware
  3. Kernel mounts root file system, which necessarily contains a program /sbin/init.
  4. Kernel executes init (the only programs the kernel ever executes explicitly, process ID 1)
  5. init scans its config file: /etc/inittab