This post shows safe, distro-agnostic ways to change the system hostname and covers common variations (systemd, init-based, NetworkManager, cloud-init, and containers).

Quick summary

  • Temporary (current session): sudo hostname <new>
  • Persistent (systemd systems): sudo hostnamectl set-hostname <new>
  • Also update /etc/hosts and check cloud-init if present.

Important: Always verify whether your environment (cloud image, container, or managed host) uses cloud-init or another management tool — it may overwrite manual changes.

1 — systemd-based systems (Ubuntu, Debian, Fedora, Arch, CentOS 7+)

  1. Set the persistent hostname:

    sudo hostnamectl set-hostname new-hostname

  2. Verify:

    hostnamectl status
hostname

  3. Update /etc/hosts to map the new hostname to localhost or the server IP to avoid issues with services that resolve the hostname:

    sudo vim /etc/hosts

    Example /etc/hosts entries:

    127.0.0.1   localhost
127.0.1.1   new-hostname    # Debian/Ubuntu local host mapping
# or use the server's IP:
192.0.2.10  new-hostname.example.com new-hostname

  4. If some services rely on the old name, either restart them or reboot:

    sudo systemctl restart systemd-hostnamed
# or
sudo reboot

2 — Older / init-style systems (non-systemd)

  1. Change the running hostname (temporary):

    sudo hostname new-hostname

  2. Make it persistent by writing to /etc/hostname (Debian-style):

    echo "new-hostname" | sudo tee /etc/hostname
sudo vi /etc/hosts   # update hosts file as above

  3. Reboot to apply fully, or run init/system-specific commands if available.

3 — NetworkManager-managed hosts

If NetworkManager manages the system hostname, use nmcli:

sudo nmcli general hostname new-hostname

Then verify with hostnamectl or hostname.

4 — cloud-init managed instances

Cloud images often use cloud-init which can overwrite manual hostname changes on next boot or reconfiguration.

  • To prevent cloud-init from overwriting your hostname, edit /etc/cloud/cloud.cfg and set:

    preserve_hostname: true

  • Or use cloud-init to set the hostname permanently (cloud-init configs vary by provider).

After changing cloud-init settings, you may need to re-run cloud-init or reboot.

5 — Containers and ephemeral environments

In containers (Docker, LXC), changing the hostname may be ephemeral and controlled by the container runtime. For Docker:

  • At container creation: docker run --hostname new-hostname ...
  • Inside a running container: hostname new-hostname (temporary)

To make changes persistent, configure the container runtime or the image startup scripts.

6 — Tips and verification

  • Display the current hostname: hostname
  • Show detailed status: hostnamectl status
  • Fully-qualified domain name: hostname -f (ensure /etc/hosts contains the FQDN)
  • Check cat /etc/hostname (on systems that use it)

7 — Troubleshooting

  • Hostname reverts after reboot: check cloud-init, orchestration tools (Ansible, Salt, Puppet), or provider metadata.
  • Services fail to start after renaming: ensure /etc/hosts maps the hostname correctly, and restart the affected services.
  • NetworkManager or DHCP resets hostname: consider configuring the client or server to stop pushing hostnames, or set the hostname via the appropriate network tool.

Automation Script

For a safe way to automate hostname changes on systemd systems, you can use this simple Bash script. Save it as change_hostname.sh, make it executable with chmod +x change_hostname.sh, and run it with sudo ./change_hostname.sh new-hostname.

#!/bin/bash

# Script to change hostname safely on systemd-based systems
# Usage: sudo ./change_hostname.sh <new-hostname>

if [ $# -ne 1 ]; then
    echo "Usage: $0 <new-hostname>"
    exit 1
fi

NEW_HOSTNAME=$1

# Backup current hostname
CURRENT_HOSTNAME=$(hostname)

echo "Changing hostname from $CURRENT_HOSTNAME to $NEW_HOSTNAME"

# Set new hostname
hostnamectl set-hostname "$NEW_HOSTNAME"

# Update /etc/hosts if necessary
if grep -q "$CURRENT_HOSTNAME" /etc/hosts; then
    sed -i "s/$CURRENT_HOSTNAME/$NEW_HOSTNAME/g" /etc/hosts
    echo "Updated /etc/hosts"
fi

echo "Hostname changed successfully. Reboot may be required for full effect."

Note: This script is basic and assumes a systemd system. Test it in a safe environment first.

Conclusion

Changing the hostname on Linux is essential for system identification and network configuration. By following the appropriate steps for your distribution and environment, you can ensure a smooth transition. Always back up configurations and test changes in non-production environments.

For more Linux administration tutorials, explore our Tutorials section!