Reprinted from: https://blog.csdn.net/liumiaocn/article/details/103170673
Narration
This article is used to introduce the five setting methods of hostname under CentOS 7. Although many methods can be used on different distributions of Linux, they are not verified in this article.
Confirm hostname method
Command to confirm the name of the current machine: hostname Current machine name setting file / etc/hostname Environment variable related to current machine name: HOSTNAME
[root@devops ~]# hostname devops [root@devops ~]# cat /etc/hostname devops [root@devops ~]# echo $HOSTNAME devops [root@devops ~]#
Method 1: use the hostname command
The current machine name is devops. Use hostname to change it to liumiao
[root@devops ~]# hostname liumiao [root@devops ~]# echo $HOSTNAME devops [root@devops ~]# cat /etc/hostname devops [root@devops ~]# hostname liumiao [root@devops ~]#
You can see that the hostname command has changed except that the prompt has not changed. After logging in again, this prompt and the hostname environment variable will change
[root@liumiao ~]# echo $HOSTNAME liumiao [root@liumiao ~]# hostname liumiao [root@liumiao ~]# cat /etc/hostname devops [root@liumiao ~]#
After restart, the status before modification will be restored
[root@devops ~]# cat /etc/hostname devops [root@devops ~]# hostname devops [root@devops ~]# echo $HOSTNAME devops [root@devops ~]#
Method 2: use the hostnamectl command
Command format: hostnamectl set hostname new name
The execution log is shown below, and you can see that all the contents except PS1 have been modified in real time
[root@devops ~]# hostnamectl set-hostname liumiao [root@devops ~]# cat /etc/hostname liumiao [root@devops ~]# echo $HOSTNAME devops [root@devops ~]# hostname liumiao [root@devops ~]#
After logging in again, you will find that the information of PS1 has changed
[root@liumiao ~]# cat /etc/hostname liumiao [root@liumiao ~]# hostname liumiao [root@liumiao ~]# echo $HOSTNAME liumiao [root@liumiao ~]#
It will not change after reboot. So hostnamectl is basically a way of changing in real time and being able to persist.
Mode 3: modify / etc/hostname
You can also change the machine name by modifying the / etc/hostname file
[root@liumiao ~]# cat /etc/hostname liumiao [root@liumiao ~]# echo $HOSTNAME liumiao [root@liumiao ~]# hostname liumiao [root@liumiao ~]#
Change it to devops and restart
[root@liumiao ~]# vi /etc/hostname [root@liumiao ~]# cat /etc/hostname devops [root@liumiao ~]# reboot Shared connection to 127.0.0.1 closed. liumiaocn:~ liumiao$
After logging in again, you can see that they have been modified
[root@devops ~]# hostname devops [root@devops ~]# cat /etc/hostname devops [root@devops ~]# echo $HOSTNAME devops [root@devops ~]#
Mode 4: modify with sysctl
Command format: sysctl kernel.hostname = new name
sysctl can also achieve the same effect by modifying the settings in the kernel. The execution log is as follows
[root@devops ~]# hostname devops [root@devops ~]# cat /etc/hostname devops [root@devops ~]# echo $HOSTNAME devops [root@devops ~]# [root@devops ~]# sysctl kernel.hostname kernel.hostname = devops [root@devops ~]# [root@devops ~]# sysctl kernel.hostname=liumiao kernel.hostname = liumiao [root@devops ~]#
The results after execution are as follows
[root@devops ~]# echo $HOSTNAME devops [root@devops ~]# cat /etc/hostname devops [root@devops ~]# hostname liumiao [root@devops ~]#
After logging back in, you can see that in addition to / etc/hostname, the HOSTNAME environment variable has also changed
[root@liumiao ~]# echo $HOSTNAME liumiao [root@liumiao ~]# hostname liumiao [root@liumiao ~]# cat /etc/hostname devops [root@liumiao ~]#
Because there is no persistent save, reboot will restore the previous state as the first method.
Method 5: modify / etc/sysconfig/network
By modifying / etc/sysconfig/network, you can also modify the return value of hostname. For example:
[root@devops ~]# cat /etc/sysconfig/network # Created by anaconda [root@devops ~]# vi /etc/sysconfig/network [root@devops ~]# [root@devops ~]# cat /etc/sysconfig/network # Created by anaconda hostname liumiao.com [root@devops ~]#
After the network service is restarted, it will take effect
[root@devops ~]# systemctl restart network [root@devops ~]# hostname liumiao.com [root@devops ~]# echo $HOSTNAME devops [root@devops ~]#
Change after login again
[root@liumiao ~]# echo $HOSTNAME liumiao.com [root@liumiao ~]# hostname liumiao.com [root@liumiao ~]# cat /etc/hostname devops [root@liumiao ~]#
In fact, hostname has two options (- F and - s: -f return FQDN value, while - s return shortname). So far, the return values of other methods are the same, but different values are returned.
[root@liumiao ~]# hostname -f liumiao.com [root@liumiao ~]# hostname -s liumiao [root@liumiao ~]#
It will not change after restart.
