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How to Change Hostname on Debian 10 Linux

This tutorial explains how to change the hostname on Debian 10 Buster without restarting the system.

The hostname is set at the time when the Debian operating system is installed or if you are spinning up a virtual machine it is dynamically assigned to the instance at startup.

Prerequisites

To be able to change the system hostname you need to be logged in as root or user with sudo privileges.

Display the Current Hostname

In Debian 10 and all other Linux distributions using systemd, you can change and display the hostname of a given system. with the hostnamectl tool.

To view the current system hostname, type hostnamectl without any option:

hostnamectl

The output will show the current system hostname, in this example that is host.linuxize.com.

   Static hostname: host.linuxize.com
         Icon name: computer-vm
           Chassis: vm
        Machine ID: 70a3f06298014fd9ac42e5dc1de1034a
           Boot ID: 1dc8b9af89a4426b99cb348f6d483757
    Virtualization: oracle
  Operating System: Debian GNU/Linux 10 (buster)
            Kernel: Linux 4.19.0-5-amd64
      Architecture: x86-64

Change the System Hostname

A hostname is a label that identifies a machine on the network. You shouldn’t set the same hostname on two different machines on a same network. It is recommended to use a fully-qualified domain name (FQDN) as the system hostname.

There are two steps involved when changing the system hostname on Debian 10. First, set the new hostname using the hostnamectl set-hostname command followed by the desired hostname and then update the /etc/hosts file with the new hostname.

For example, to change the system hostname to arya.example.com, you would do the following steps:

  1. First set the new hostname by running:

    sudo hostnamectl set-hostname arya.example.com

    The hostnamectl command does not produce output. On success, 0 is returned, a non-zero failure code otherwise.

  2. Second, open the /etc/hosts file and replace the old hostname with the new one.

    /etc/hosts
    127.0.0.1   localhost
    127.0.0.1   arya.example.com arya 
    
    # The following lines are desirable for IPv6 capable hosts
    ::1     localhost ip6-localhost ip6-loopback
    ff02::1 ip6-allnodes
    ff02::2 ip6-allrouters

Verify the Change

To verify that the hostname was successfully changed, once again use the hostnamectl command:

hostnamectl

The new system hostname will be printed on the command line.

   Static hostname: arya.example.com
         Icon name: computer-vm
           Chassis: vm
        Machine ID: 70a3f06298014fd9ac42e5dc1de1034a
           Boot ID: 1dc8b9af89a4426b99cb348f6d483757
    Virtualization: oracle
  Operating System: Debian GNU/Linux 10 (buster)
            Kernel: Linux 4.19.0-5-amd64
      Architecture: x86-64

Conclusion

Changing system hostname on Debian 10 Buster is an easy task, involving only two simple steps.

Feel free to leave a comment if you have any questions.