1.13 Single-user mode 1.14 Rescue mode 1.15 clone virtual machine 1.16 Linux machines log in to each other

1.13 Single-user mode

1, single-user mode is mainly used to forget the root password;

Restart Device: Reboot;init6;shutdown-r now

Shutdown: Init 0;poweroff

Reboot the device into the following States:

Select the upper and lower direction keys;

Press the E key to enter the Grub interface

Locate the system boot disk, boot the hard disk, load the kernel, etc.

Find Ro,ro indicates read only;

Change RO to RW, show-read/write

Overriding the RW parameter

Press Ctrl+w

Change Password:

An important step:

Restart your device and log in with your new password

1.14 Rescue Mode

1. Rescue mode

[Email protected] ~]# ls-l/usr/lib/systemd/system/runlevel*target

lrwxrwxrwx. 1 root root 2017/usr/lib/systemd/system/runlevel0.target-Poweroff.target

lrwxrwxrwx. 1 root root 2017/usr/lib/systemd/system/runlevel1.target-Rescue.target

lrwxrwxrwx. 1 root root 2017/usr/lib/systemd/system/runlevel2.target-Multi-user.target

lrwxrwxrwx. 1 root root 2017/usr/lib/systemd/system/runlevel3.target-Multi-user.target

lrwxrwxrwx. 1 root root 2017/usr/lib/systemd/system/runlevel4.target-Multi-user.target

lrwxrwxrwx. 1 root root 2017/usr/lib/systemd/system/runlevel5.target-Graphical.target

lrwxrwxrwx. 1 root root 2017/usr/lib/systemd/system/runlevel6.target-Reboot.target

Divided into 6 levels;

When restarting, note:

Loading the optical drive at startup

Restart after rebooting into BIOS setup

There are 4 ways to choose,

This is another change to the root password, using the form of a disc;

If you change the wrong file, you can enter the rescue mode, the wrong file is changed correctly;

1.15 Cloning a virtual machine

Cloning of VMS

Shut down the VM, then click Manage-Clone

Log in to a new VM

Then modify the IP address of the new VM, otherwise it will cause IP conflicts;

The UUID is deleted and the new IP address is configured;

Then restart the Network service

#systemctl Restart Network.service

Ifconfig

View the IP address,

Then reset hostname, host name

Then exit the login again and the hostname has changed

To change the configuration file for a host name

Changing the hostname is actually a configuration file that changes the host name

1.16 Linux machines log in to each other

1.2 servers log in to each other

If 2 servers are logged in to each other, using the SSH service, is the SSH password-free login method,

1. Server B connects to server A

2. Generate a key pair on Server B;

[Email protected] ~]# Ssh-keygen

,. Ssh/id_rsa is the private key;. ssh/id_rsa.pub-is the public key;

Then the contents of the public key are copied to A;

Turn off SELinux

Log on to server a directly from server B without a password

1.13 Single-user mode 1.14 Rescue mode 1.15 clone virtual machine 1.16 Linux machines log in to each other