Display the current CentOS 8 hostname

Type any one of the following command:
$ hostname
OR
$ hostnamectl

CentOS 8 change hostname command

The procedure to change the computer name on CentOS Linux:

1. Type the following command to edit /etc/hostname using nano or vi text editor:
   sudo vi /etc/hostname
2. Delete the old name and setup new name.
3. Next Edit the /etc/hosts file:
   sudo vi /etc/hosts
4. Replace any occurrence of the existing computer name with your new one.
5. Reboot the system to changes take effect:
   sudo reboot

How to change the CentOS 8 server hostname without a system restart

Type the following commands:
$ sudo hostname nixcraft-centos8
Next edit the /etc/hostname file and update hostname:
$ sudo vi /etc/hostname
Finally, edit the /etc/hosts file and update the lines that reads your old-host-name:
$ sudo vi /etc/hosts
From:
127.0.1.1 localhost
To:
127.0.1.1 nixcraft-centos8
Save and close the file.

A note about hostnamectl command

Systemd based Linux distributions such as CentOS 8 can simply use the hostnamectl command to rename hostname. To see current setting just type:
$ hostnamectl
Sample outputs:

   Static hostname: localhost.localdomain
Transient hostname: li2025-143.members.linode.com
         Icon name: computer-vm
           Chassis: vm
        Machine ID: 3e729c2d7c094902af0333ce40564ffe
           Boot ID: e359e65f68ff45f2825134354bdc0a8d
    Virtualization: kvm
  Operating System: CentOS Linux 8 (Core)
       CPE OS Name: cpe:/o:centos:centos:8
            Kernel: Linux 4.18.0-80.7.1.el8_0.x86_64
      Architecture: x86-64

To change hostname from localhost.localdomain to nixcraft-centos8, enter:
$ sudo hostnamectl set-hostname nixcraft-centos8
$ hostnamectl

Conclusion

On CentOS 8 one can use the hostnamectl command to control the system hostname and set a new name as well. This is recommended method for all CentOS 8 users.