How to Change Hostname on CentOS 7

On this short tutorial, we will learn how to change hostname on CentOS 7 operating system.

Introduction

As a sysadmin, we are sometimes asked by our user to reset the hostname of a server. It doesn’t matter whether the system we are going to change the hostname for is in the cloud, virtual machine or on premise.  On this article, we will discuss how to change the hostname on the CentOS 7 operating system.

The steps to change the hostname are as follows :

1. Checking Current Hostname
2. Change Hostname
3. Update /etc/hosts
4. Confirm the Change

1. Checking Current Hostname

On this stage, we will check current hostname This task can be performed by submitting command line hostname atau hostnamectl.

$ hostnamectl

Output :

[ramansah@localhost /]$ hostnamectl
Static hostname: localhost.localdomain
Icon name: computer-vm
Chassis: vm
Machine ID: 0b99206d488246ab9454bb64a579545d
Boot ID: 6813bffc38614b4dbbb667a7488fa097
Virtualization: vmware
Operating System: CentOS Linux 7 (Core)
CPE OS Name: cpe:/o:centos:centos:7
Kernel: Linux 3.10.0-1160.el7.x86_64
Architecture: x86-64

2. Set New Static Hostname

On this stage, we will set a new static hostname. CentOS 7 only allows Fully Qualified Domain Names (FQDNs), for this purpose will do the following steps :

$ sudo hostnamectl set-hostname <new_hostname>

On this tutorial, we will use dev01.bckinf.com as new hostname. Outpu of this command is shown below.

[ramansah@localhost /]$ sudo hostnamectl set-hostname dev01.bckinfo.com

3. Verify the Hostname

Then we will verify again, the last hostname after changing, by submitting command line hostnamectl.

[ramansah@localhost /]$ hostnamectl
Static hostname: dev01.bckinfo.com
Icon name: computer-vm
Chassis: vm
Machine ID: 0b99206d488246ab9454bb64a579545d
Boot ID: 6813bffc38614b4dbbb667a7488fa097
Virtualization: vmware
Operating System: CentOS Linux 7 (Core)
CPE OS Name: cpe:/o:centos:centos:7
Kernel: Linux 3.10.0-1160.el7.x86_64
Architecture: x86-64

[ramansah@localhost /]$ hostname
dev01.bckinfo.com

4. Edit the /etc/hosts File

On this stage, we will update /etc/hosts file to change hostname persistently.

[ramansah@localhost /]$ sudo vi /etc/hosts

In the text editor, look for the line that begins with 127.0.0.1 (the IP address that refers to the system you are working on). It should read:

127.0.0.1 localhost localhost.localdomain localhost 4 localhost4.localdomain4 old.hostname

In this step we have to change the entry old.hostname to my.new-hostname.server – and spell it the same as in Step 2.

127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6

to  be

127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
127.0.0.1 dev01 dev01.bckinfo.com
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6

After all are set, then we reboot the system, and check again by using command line hostnam or hostnamectl.

Conclusion

On this short article, we have learned how to change hostname on CentOS 7 operating system. I hope this guidance will be helpful.