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Editor to share with you how centos7 switch boot kernel and switch boot mode, I believe that most people do not know much about it, so share this article for your reference, I hope you can learn a lot after reading this article, let's learn about it!

Centos7 switch Boot Kernel

Note: it is recommended that if necessary, you can first execute yum update-y to upgrade all software packages

Note:

1. The CentOS I used for testing is version 7.2. the installation is minimized by default, and the system kernel is 3.10.0-327.

2. After upgrading to 4.4.x, if you randomly use the yum update-y command to upgrade the software, you will continue to install the 3.10.0-693kernel package in CentOS7.4 as the first startup item.

3. After each yum update-y, you need to use the grub2-set-default 0 command to modify the default kernel startup entry. 0 bit is the first item, 1 is the second item, and so on. Check the GRU.

1. View the current system kernel

Uname-r

3.18.6-2.el7.centos.x86_64

View a list of available kernels

Awk-F\'$1 etc/grub2.cfg = "menuentry" {print iTunes + ":" $2}'/ etc/grub2.cfg

The results are as follows:

0: CentOS Linux (3.18.6-2.el7.centos.x86_64) 7 (Core)

1: CentOS Linux (3.10.0-514.el7.x86_64) 7 (Core)

2: CentOS Linux (0-rescue-05653d304ed443db9b60529d6cf7d242) 7 (Core)

2. View the current default kernel startup items

Grub2-editenv list

The results are as follows:

Saved_entry=0

That is, the default kernel loaded when the system starts is CentOS Linux (3.18.6-2.el7.centos.x86_64) 7 (Core).

3. Change the default startup kernel entry

Grub2-set-default 1

Look at the default kernel startup item again and find that the saved_entry field has changed to 1

4. Restart the system

Reboot

View the current system kernel

Uname-r

3.10.0-514.el7.x86_64

You can see that the kernel of the current system has changed

Centos7 toggles startup mode

First, there are only two startup modes for centos:

Multi-user.target: analogous to runlevel 3 # command line mode graphical.target: analogous to runlevel 5 # graphics mode

Check the vim / etc/inittab file. There are commands to change the mode.

Second, view the current mode:

Systemctl get-default

Third, change the startup mode

Start as a command:

Systemctl set-default multi-user.target

Start graphically:

Systemctl set-default graphical.target above is all the contents of the article "how to switch between boot kernel and boot mode in centos7". Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!

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