The boot process - sysvinit

System

Power On

BIOS or EFI loads

BIOS scans and hands off to the primary disk's boot sector

Boot sector provides the MBR within the first 512 bytes of the active drive

Boot loader is executed:

LILO/GRUB/GRUB2

USER INPUT (choose boot types or kernel versions or allow default to proceed)

Linux kernel is read and executed

Root file system is mounted

The init program loads and becomes the first PID - /sbin/init

/etc/inittab is read and the appropriate runlevel scripts are run

Root fylesystem is checked

Remaining local filesystems are mounted

Network devices are started

Remote filesystems are mounted (if configured)

Device initialization, module loading, and initial RAM disk (initrd) is loaded

Modules indicated within the init scripts are loaded

Init process rescans /etc/inittab and changes/sets the system to the indicated default runlevel and completes execution of appropriate scripts

Runlevel scripts are executed in numeric order

TTY sessions are loaded (as listed in /etc/inittab)

System login prompt is displayed on console, system is ready for login