Shulou(Shulou.com)06/02 Report--

CentOS6 start-up process:

1. Load BIOS hardware information and get the first boot device

2. Read boot information for the boot loader (grub) of the first boot device MBR

3. The kernel information of the kernel operating system is loaded, and the kernel begins to decompress and try to drive all hardware devices

4. The kernel executes the init program and gets default runtime information

5.The init program executes the/etc/rc.d/rc.sysinit file

6. Start the core plug-in module

7.init Executes Run Batch Files (scripts)

8.init Execute/etc/rc.d/rc.local

9. Execute the/bin/login program and wait for the user to log in

10. After logging in, start controlling the host with Shell

CentOS 7

Boot sequence UEFi or BIOS initialization, run POST

Select Start Device

Bootloader, centos7 is grub2

Load loader configuration file:

/etc/grub.d/

/etc/default/grub

/boot/grub2/grub.cfg

Loading the initramfs driver module

Load kernel options

Kernel initialization, centos7 uses systemd instead of init

Execute initrd.target All units, including mount/etc/fstab Switch from initramfs root file system to disk root directory

systemd executes default target configuration, configuration file/etc/systemd/system/default.target

systemd executes sysinit.target initializes the system and basic.target prepares the operating system

systemd starts native and server services under multi-user.target

systemd Execute/etc/rc.d/rc.local under multi-user.target

Systemd executes getty.target and login services under multi-user.target

systemd performs graphical needs

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