Linux system boot level and grub configuration (i)

I. Linux system start-up process

1. First computer power-on self-test, into the BIOS, through the MBR load bootloader, and then by the bootloader load kernel in memory to complete the decompression, then the control to the kernel, the kernel to complete the detection of hardware and then access INITRD, and then execute the INIT process

2.Linux system is a single core, it has a kernel module and other peripheral modules, peripheral modules in the/lib/modules/kernel version number named directory/down

3. Establish a separate small system on the existing system

A. Create a test root directory under the root home directory

mkdir-pv/root/test/vimroot//root/test/vimroot/{lib,bin}

B. Copy the/bin/bash file to the/root/test/vimroot/bin/directory

cp/bin/bash/root/test/vimroot/bin/

You can use the which command to see where a binary file is.

Which bash

C. Use the LDD command to see which library files The bash file depends on

Ldd/bin/bash

d. Copy dependent library files to the appropriate directory

cp/lib/libc.so.6/root/test/vimroot/lib/

E. Switching the root file system with the chroot command

chroot/root/test/vimroot/

Operating level--runlevel at 4.Linux

Operating level: 0-6

0:halt (OFF)

1:single user mode, log in directly as Administrator (single user mode), s,s,single,1

2:multi user mode, no NFS (multi-user mode with network function)

3:multi user mode, text mode (multi-user mode, character interface)

4:reserved (Reserved level)

5:multi user mode, graphic mode (multi-user mode, graphical interface)

6:reboot (restart)

5./etc/inittab file Set default run level

Id:3:initdefault:

6.bootloader (MBR master boot Record)

Lilo:linux Loader: Large hard drives are not supported, but used in embedded systems

Grub:grand Unified Bootloader

Stage1: in MBR

Stage1_5: Used to identify different file systems

Stage2: In/boot/grub/

/etc/grub.conf file

Default=0 # Sets the number of the default start title, numbering starting from 0

Timeout=5 # waits for the user to select the timeout length, in seconds

Splashimage= (hd0,0)/grub/splash.xpm.gz # Grub Background image

Hiddenmenu # Hidden Menu

Password--md5 $1$hkxj51$b9z8a. X//xa. Atzu1.kug. # To set the password for grub, must precede the title

Title Red Hat Enterprise Linux Server (2.6.18-308.el5) # kernel header, or operating system name, string, can be freely modified

Root (hd0,0) # The device where the kernel file resides. For grub, all types of hard drives are HD, in the format (hd#,n); hd#, #表示第几个磁盘; the last N indicates the partition of the corresponding disk

Kernel/vmlinuz-2.6.18-308.el5 ro root=/dev/vol0/root rhgb quiet # Kernel file path, and parameters passed to the kernel. In the/proc/cmdline file

INITRD/INITRD-2.6.18-308.EL5.IMG # RAMDisk file path, mirror device file

7. Set the grub password using the Grub-md5-crypt command

RunLevel command--view run level

Who-r--View current run level

uname-r--viewing the kernel version number

8. Install GRUB (grub corruption, fix grub)

A. Manual damage bootloader

DD If=/dev/zero OF=/DEV/SDA bs=400 count=1

B. Go to the GRUB command line and install Grub STAGE1

Grub

C. Specify the partition where the kernel resides

grub> Root (hd0,0)

D. Install grub and specify to install on that disk

Grub> Set (hd0)

E. Then restart the

Shutdown-r now

Install grub the second way:

# Grub-install--root-directory=/path/to/boot ' S_parent_dir/path/to/device

This article is from "Luo Chen's blog" blog, please be sure to keep this source http://luochen2015.blog.51cto.com/9772274/1650105

Linux system boot level and grub configuration (i)