Start the process 1, CentOS6 the
POST Power On Self Test: When this process is turned on, BIOS or UEFI hardware inspection stage
2, the guide MBR: the first 446 bytes of the first sector of the hard disk to find the BIOS, the MBR loaded into memory, the MBR tells the program where to find the next phase grub guide system, this stage is the first stage grub
3, GRUB boot: the first 2 and 1.5 grub stage. In order to load the kernel system, you have to load / boot partition, load / boot partition need / boot drive partition. Drive / boot partition is on the / boot partition, so Linux to start relying on the 1.5 stage data
stage1 stage: MBR saved in the first 446 bytes.
stage1.5 stage: it saves the sector after the MBR. The purpose is to enable the boot loader to recognize the file system on the partition stage2 stage is located.
stage2 stage: save disk partition / boot / grub / directory, which contains the required boot kernel file, virtual disk image file and other system
critical files used.
4. Read grub.conf file: start determining the kernel parameter
5. Start the kernel:
load the kernel, the core began to decompress. Some of the most core of the program start
using initramfs-2.6.32-754.el6.x86_64.img to drive hardware
6. Load pseudo file system (ramdisk): kernel has started up, then call ramdisk (initramfs-2.6.32-754.el6.x86_64.img) file, try to drive all the hardware devices, to this point, the kernel up, All drivers are also installed on the back of the program to be able to start the
production ramdisk file: mkinitrd / boot / initramfs - $ (uname -r) .img $ (uname -r)
7. Start init process:
GRUB specified in init = / sbin / init program
(1) read / etc / inittab file
inittab file defines the system default run level, this step is mainly to do some work as follows:
A) Initial run level (the rUN the lEVEL)
B) system initialization script
c) corresponding to run-level scripts directory
d) define the UPS power supply terminal / recovery script
e) generating a getty virtual console to generate the terminal
f) X initialized at run level 5
(2) /etc/rc.d/rc.sysinit program execution
system initialization scripts, mainly to complete the following tasks
a) set the hostname
b) a banner
c) may activate udev and selinux in grub.conf, add the kernel line selinux = 0 to turn off SELinux
D) mounted / etc / fstab file in the file system defined in
e) detecting the root file system, and read-write remount the root filesystem
f) set the system clock
g) activate the swap device
h) the kernel parameter setting file /etc/sysctl.conf
i) and activated software raid lvm device
drivers to load additional equipment J)
K) the cleaning operation
(3) /etc/rc#.d/ file (services)
which are defined by a variety of services startup script, you can see ls, S for start-up services. K is shut down at the beginning of the task to be performed. # Represents a number
(4) /etc/rc.d/rc.local file
there can boot from the command definition
8, execute / bin / login
execute / bin / login program, waits for the user to log
grub安装
grub-install --root-directory=DIR /dev/DISK
例：grub-install --root-directory=/mnt /dev/sdb
Finishing wrong question:
1, linux systems view modules currently loaded? View ⼀ module information and related parameters Remedies? Load ⼀ modules?
(1) View loaded modules
lsmod command
(2) displaying information kernel module
modinfo command
(3) to load a module
modprobe command
2, how to view the BIOS version, the machine model, serial number on the linux system? View ⽹ card driver version?
biosdecode BIOS version command
View server models: dmidecode | grep 'Product Name'
Check the motherboard serial number: dmidecode | grep 'Serial Number The'
ethtool -i ens33 network card driver version