Changing the hostname in CentOS, Ubuntu

Intro

Changing a computer's name is a common thing to do.

This is how.

Guide

To change the hostname permanently, follow these steps.

For CentOS

1. Edit /etc/sysconfig/network.

   # nano /etc/sysconfig/network

2. Change the HOSTNAME.

   HOSTNAME=newHostname

3. Save and exit.
   
   
4. Edit /etc/hosts

   # nano /etc/hosts

5. Add a new line.

   127.0.0.1 newHostname

6. Save and exit.
   
   
7. Restart the network daemon.
   For CentOS 6 and older:

   # service network restart

   
   For CentOS 7 and newer, as well as for most Ubuntu-distros:

   # systemctl restart NetworkManager

8. If restarting the network didn't or won't change the hostname for some reason, try restarting the computer.

   # shutdown -r now

9. Confirm the name change.

   # hostname
   newHostname

For Ubuntu

1. Edit /etc/hosts.

   # nano /etc/hosts

2. Add a new line.

   127.0.0.1 newHostname

3. Save and exit.
   
   
4. Run hostnamectl to check the name.

   # hostnamectl
   Static hostname: oldHostname
    Icon name: computer-desktop
    Chassis: desktop
    Operating System: Ubuntu 18.04.1 LTS
    Kernel: Linux 4.15.0-43-generic
    Architecture: x86-64

5. Nope, not yet set. So we run hostnamectl again, but this time with a couple of parameters.

   # hostnamectl set-hostname newHostname

6. And a confirmation.

   # hostnamectl
   Static hostname: newHostname
    Icon name: computer-desktop
    Chassis: desktop
    Operating System: Ubuntu 18.04.1 LTS
    Kernel: Linux 4.15.0-43-generic
    Architecture: x86-64

Sources

https://unix.stackexchange.com/questions/145019/how-to-change-hostname-on-centos-6-5

https://support.rackspace.com/how-to/centos-hostname-change/

https://linuxize.com/post/how-to-change-hostname-on-ubuntu-18-04/