How to change hostname in Linux

Changing the hostname gives a Linux machine a stable identity in shell prompts, logs, inventory, monitoring, and remote-management tools. Renaming a fresh install that still uses a generic name such as host is a common cleanup task after provisioning a new VM, cloud instance, or physical server.

On current systemd-based systems such as Ubuntu Server 24.04, hostnamectl talks to systemd-hostnamed to manage the host name. Updating the hostname this way changes the running system immediately and writes the persistent static value to /etc/hostname, which takes precedence over transient names learned from DHCP or other network configuration.

The examples here target a current Ubuntu server. Use a lowercase DNS label such as web-01 unless your environment requires a fully qualified domain name. On Ubuntu-style installs, check /etc/hosts afterward because the old short name may still be mapped on 127.0.1.1, and treat a hostname that changes back later as a sign that cloud-init or configuration management still owns the system identity.

1. Review the current hostname state and confirm that hostnamectl is available on the host.

   $ hostnamectl status
    Static hostname: host
          Icon name: computer-vm
            Chassis: vm
   Operating System: Ubuntu 24.04.3 LTS
             Kernel: Linux 6.8.0-90-generic

   If hostnamectl is missing or the system bus is unavailable, this machine uses a different hostname-management path and these steps do not apply unchanged.

2. Set the new hostname with hostnamectl.

   $ sudo hostnamectl hostname web-01

   Use a single lowercase DNS label such as web-01 unless the environment standard requires a fully qualified domain name such as web-01.example.net.

   If the old hostname appears in DNS records, SSH trust, TLS certificates, monitoring targets, or configuration-management data, update those references separately before treating the rename as complete.

3. Confirm that the running host and the persistent hostname file now show the new name.

   $ hostnamectl --static
   web-01
   
   $ hostname
   web-01
   
   $ cat /etc/hostname
   web-01

   If /etc/hostname does not match hostnamectl –static, or the name reverts later, another management layer such as cloud-init or configuration management is rewriting it.

4. Check whether Ubuntu still maps the old short name on 127.0.1.1 in /etc/hosts.

   $ grep -n '127.0.1.1' /etc/hosts
   2:127.0.1.1 host

   If this command prints nothing, there is no host-specific local mapping to change on this system.

5. Update the 127.0.1.1 line in /etc/hosts if the previous step still showed the old name.

   $ sudoedit /etc/hosts

   127.0.0.1 localhost
   127.0.1.1 web-01

   Keep the localhost entries unchanged and replace only the host-specific hostname fields on the 127.0.1.1 line.

   Related: How to edit the hosts file in Linux