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Today, I will show you how to analyze the CentOS 7 boot process and service management. The content of the article is good. Now I would like to share it with you. Friends who feel in need can understand it. I hope it will be helpful to you. Let's read it along with the editor's ideas.

First, the guiding process

Linux operating system boot process: post → MBR boot → GRUB menu → load Linux kernel and memory file system → load hard drive and initialization process.

Introduction to CentOS 7 Boot process and Service Management introduction to CentOS 7 Boot process and Service Management

1), post

After the server is booted, the CPU, memory and other hardware devices will be initially tested according to the settings in the motherboard BIOS, and some of the hardware will be initialized. After completion, the control of the system will generally be handed over to the local hard disk.

2), MBR boot

When booting the system from the local hard disk, first transfer the system control to the partition containing the operating system boot file according to the MBR setting in the first sector of the hard disk, or call the boot menu directly according to the boot information in the MBR record. MBR is closely related to our normal boot, so we need to back up MBR in advance in case we need it from time to time.

3), GRUB menu

For Linux systems. GRUB is the most widely used multi-system loader program. After system control is transferred to GRUB, we select the system we need, and then load the kernel file of the relevant system.

4) load Linux kernel and memory file system

When system control comes to the kernel, the program bootstrap loads the kernel and memory file system from the local hard disk.

5) load hardware drivers and initialize processes

The kernel and file system switch from the in-memory file system to the system root file system and rerun / sysroot.systemd. Start the default graphics or character terminal and finally wait for the user to log in.

Second, use systemd management system

1. Systemd unit

In systemd, different types of systemd objects are called units, and they are the main objects that let the system know how to manipulate and manage resources, so systemd has many unit types. Common systemd unit types

Introduction to CentOS 7 Boot process and Service Management introduction to CentOS 7 Boot process and Service Management

2. Systemd process

The systemd process is the "brain" that maintains all the processes running in the whole Linux system, so the systemd process is not allowed to be terminated easily. When you need to switch different system running states, you can send the correct command to the systemd process by systemd itself to complete the relevant operations.

The above is how to analyze all the contents of CentOS 7 boot process and service management. For more information about how to analyze CentOS 7 boot process and service management, you can search the previous articles or browse the following articles to learn! I believe the editor will add more knowledge to you. I hope you can support it!

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