Shulou(Shulou.com)06/01 Report--

This article mainly introduces "CentOS system single user mode introduction". In daily operation, I believe many people have doubts about CentOS system single user mode introduction. Xiaobian consulted various materials and sorted out simple and easy operation methods. I hope to help you answer the doubts of "CentOS system single user mode introduction"! Next, please follow the small series to learn together!

CentOS system enters single user mode

Single user mode requires CentOS system bootloader to work properly. The following is an example of GRUB entry. In the GRUB boot menu, there are three operation keys "a,""e" and "c," which can be used to enter single user mode.

Use the "a" operation key to enter single user mode---Recommended: Simple operation

This is the quickest way to get CentOS into single-user mode. In the GRUB boot menu, use the "a" action key to edit kernel parameters. Enter single at the end of the line to tell the Linux kernel that subsequent boot processes need to enter single-user mode. Enter.

After entering single user mode

When CentOS system enters single user mode, no user name and password need to be entered. After CentOS system is started, it will directly obtain the permission of administrator root, and the prompt of console is "#".

Console Interface in Single User Mode

Remounting root filesystem in read-write mode: [OK] indicates that the CentOS root file in single-user mode is readable and writable at this time. CentOS system administrators can maintain the system only if the root file system is read-write. If there are errors in the system configuration and script files, the root file system in single-user mode enters the read-only state. At this time, you can mount the root file system read-write by using the following command:

sh-3.1 # mount -o remount rw -t ext3 /

When CentOS enters single-user mode, since any network services and network configuration have been stopped (network interfaces are invalid), no one else (through the network) can interfere with the running state of CentOS, and administrators can safely perform system-level maintenance operations on CentOS. CentOS is a fully functional operating system in single-user mode, except that it does not have network functionality. The following maintenance and administration tasks can be performed in single-user mode:

Reset superuser password

Maintains CentOS system partitions, LVM, file systems, etc.

Backup and restore CentOS systems

A typical application of single-user mode is root's "password settings." For some CentOS systems that are temporarily used or used for experiments (such as student labs), users are often changed, and the password of the root user may be lost. In this case, you can enter the single user mode to change the password of the root user.

sh-3.1 # passwd

Changing password for user root.

New UNIX password:

Retype new UNIX password:

passwd: all authentication tokens updated successfully. When CentOS enters single-user mode, execute passwd at the "#" prompt to update the root password. When CentOS restarts, you can log in as root with the updated password.

At this point, the study of "Introduction to CentOS System Single User Mode" is over, hoping to solve everyone's doubts. Theory and practice can better match to help everyone learn, go and try it! If you want to continue learning more relevant knowledge, please continue to pay attention to the website, Xiaobian will continue to strive to bring more practical articles for everyone!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.