Linux Series Part 1: Boot Process

Hello readers,nowadays DevOps is very growing technology and important for automation. Linux is one of fundamental concept of DevOps. from this blog I am going to start one linux understanding series which will be having basic fundamentals of linux ,its structure and its working.

Boot Process:

Source: Geeks For Geeks

Step 1: power on

Step 2: BIOS

• Perform system integrity check
• Search, load, execute bootloader program for hard drive

Step 3: MBR (master boot record)

• Three sections (primary bootloader, partition table info, MBR validation check)
• Less than 512 bytes size
• Located in bootable disk
• Contain info about grub
• Loads and executes grub boot loader

Step 4: GRUB

• You can choose which kernel image execute
• Display splash screen
• Loads default kernel image

Step 5: Kernel

• Executes init program located in /sbin/init
• Loads file system and execute first program

Step 6: init

• Decides the linux runlevels
• Runlevels are 0,1,2,3,4,5,6

Step 7: run level

• S and K Scripts
• S -> Startup Scripts
• K -> Stopping scripts