How to Change the Hostname in Debian 12 BookWorm

Debian 12 Bookworm Host Name Modification Guide

In the world of network-connected computers, each device needs a unique identifier—the host name—to distinguish different devices. Whether you are working on a large enterprise network or just operating on a personal Linux system, you may need to change the hostname. This guide will detail how to change the hostname in the latest version of Debian 12 Bookworm, the popular Linux distribution.

Preparation

Before you begin, make sure you meet the following conditions:

1. Terminal access permission: Remote access to the terminal through the graphical user interface or SSH.
2. Superuser or sudo permissions: Administrator permissions are required to make system-wide changes.
3. Basic Linux command line knowledge: It will be very beneficial to know how to operate a terminal.
4. Installed Debian 12 Bookworm system: This guide is for this specific version.

Explanation of terms

To ensure that we understand consistently, let's clarify some terms:

1. Host name: The tag assigned to the machine on the network.
2. Superuser: Administrator with full access to Linux system.
3. sudo: Allows authorized users to execute commands as superusers.
4. /etc/hostname and /etc/hosts: Configuration files that store host name information.

Backup the current settings

Backing up important configurations is always a prudent approach before making any changes. Open the terminal and run:

 cp /etc/hostname /etc/hostname.bak
cp /etc/hosts /etc/hosts.bak

This will create a backup copy of the current hostname and hosts file.

Method 1: Use the hostnamectl command

Step 1: Check the current host name

To view the current host name, run the following command:

 hostnamectl

Step 2: Change the host name

To change the hostname, execute:

 sudo hostnamectl set-hostname new hostname

Replace "New Host Name" with the host name you want. For example, to change the hostname to "mydebian", you will run:

 sudo hostnamectl set-hostname mydebian

Step 3: Verify the changes

Use the hostnamectl command again to check whether the hostname has been updated:

 hostnamectl

Method 2: Manually edit the configuration file

Step 1: Open /etc/hostname file

Open the /etc/hostname file using a text editor (such as nano):

 sudo nano /etc/hostname

Step 2: Edit the host name

In the text editor, you will see the current hostname. Delete and replace it with your new hostname, then save and exit.

Step 3: Open and edit the /etc/hosts file

Similarly, open the /etc/hosts file:

 sudo nano /etc/hosts

Find the line that starts with 127.0.1.1 and is followed by the old host name. Replace the old hostname with the new hostname, save and exit.

Step 4: Apply changes

After making these changes, apply them using the following command:

 sudo systemctl restart systemd-hostnamed

Step 5: Verify the changes

To check if the hostname has been changed successfully, run:

 hostnamectl

Frequently Asked Questions

Host Name Not Updated: If you find that the host name is not Updated immediately, a system restart can usually resolve this issue:

 sudo reboot

Network Service Issue: After changing the hostname, you may find that some network-related services are running abnormally. Restarting the network service usually solves this problem:

 sudo systemctl restart networking.service

Summarize

You have now mastered two different ways to change the hostname in Debian 12 Bookworm: using the hostnamectl command and manually editing the configuration file. While the hostnamectl method is faster and easier, understanding the configuration file gives you a deeper understanding of how Linux systems work.

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