The Linux booting process begins with the BIOS performing basic checks before activating the MBR, which then loads the boot loader GRUB. GRUB executes the Linux kernel, which loads the root file system, init, device drivers, and runlevels to start Linux in single-user, multi-user, or graphical mode.

1. LINUX BOOTING PROCESS
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2. BIOS
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BASIC INPUT OUT PUT SYSTEM
PERFORMS BASIC SYSTEM INTEGRITY TEST
ALSO CALLED AS POST (POWER ON SELF RTEST)
ACTIVATES MBR

3. MBR
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MASTER BOOT RECORD
LOCATED AT FIRST SECTOR OF THE BOOTABLE DEVICE
ACTIVATES GRUB OR BOOT LOADER

4. GRUB
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GRAND UNIFIED BOOT LOADER
EXECUTES KERNEL

5. KERNEL
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CORE OF LINUX SYSTEM
LOADS ROOT FILE SYSTEM, INIT AND ALL DEVICE DRIVERS

6. INIT
INITIATE THE RUNLEVEL REFFERING TO THE /ETC/INITTAB
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7. RUNLEVEL
NOTHING BUT MODE OF OS TO BE BOOTED
0 - IS FOR HALT
1 – FOR SINGLE USER MODE
2 - MULTIUSER WITHOUT NETWORK
3 - MULTI USER WITH NETWORK
4- UNUSED
5 - X11 OR GRAPHICAL MODE
6 - REBOOT
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