Linux Interview Question Boot Process for Linux
What is the boot process for Linux? It is the most asking question in Linux Interview. If you are learning Linux System Administration, you should know the boot process of Linux.
Here I will explain about boot process for Linux in a simple language. First, you press the power button in Linux server computer after some time you will get a login screen. Do you know what is happening behind this process?
From pressing the power button to display the login screen, the process is happening is called the Boot Process. This boot process performs in six different stages.
First Process: BIOS(Basic Input/Output System)
After pressing power button BIOS to check all input-output related hardware system integrity. If it is ok then Searches, loads, and executes the boot loader program called MBR.
Second Process: MBR (Master Boot Record)
MBR located in the first sector of a bootable disk. It has an information boot related file called GRUB. MBR execute GRUBboot loader.
Third Process: GRUB (Grand Unified Bootloader)
GRUB has information about a filesystem. GRUB just loads and executes kernel and initrd image.
Fourth Process: Kernel
Kernel executes the /sbin/init program.
Fifth Process: Init
Init identifies the default initlevel from /etc/inittab and uses that to load all appropriate program.
Sixth Process: Run Level
There are 7 run levels in which the Linux Operating System runs and different run levels serve for the different purpose. As per selected run level, Operating System Start loading and run the related program.
[ I hope you will understand the basic concept of the boot process for the Linux Operating System. ]
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