How to change the hostname on an Ubuntu server using the command line

What is a hostname in Linux?

A Linux hostname is a unique name given to a device on a network. It is used to identify and communicate with other devices on the network.

A fully qualified name (FQDN) is the complete domain name for a device, including the hostname and the domain name.

If you’re using just a single computer that’s not part of a network, then just the hostname is applicable.

Other systems such as WHM and Virtualmin needs the FQDN to be correct too. With WHM is easy with the UI to change the hostname, but with Virtualmin it’s best to set the correct name before installing the control panel software.

Be careful of making the hostname of WHM or Virtualmin the same as an existing working domain – rather separate the hostname to something that will only be used to access the host. WHM warns you about this, and Virtualmin will have Postfix issues if the hostname is the same as a working domain.

How to see the current hostname

The commands you would use to interrogate the hostname and FQDN are:

hostname --fqdn

All three those should return the correct results.

Furthermore, after a perfect setup, your /etc/hosts file should look like this:

root@host:~# cat /etc/hosts
... host localhost

Additionally your /etc/hostname file should look like this:

root@host:~# cat /etc/hostname 

How to change the hostname

Changing the hostname on Ubuntu needs to happen in two places to make it permanent:




In /etc/hosts look for: old-host-name

and change to new-host-name

If you prefer fully qualified, which is better, do this: new-host-name

Finally to make it stick for now, do this:

hostname new-host-name

If you have a terminal open already, it won’t change the current signature so you’ll have to open a new terminal.

Additional Information

There are more places to look for the hostname excpet looking at /etc/hostname and /etc/hosts  and the hostname command Here are the various places you have to go and look to change the hostname:

hostnamectl displays the current hostname, for example:

# hostnamectl
Static hostname: eugene-nuc
Icon name: computer-desktop
Chassis: desktop
Machine ID: b76cc7b1bbdc489e93909d2043031de8
Boot ID: ba0a677263cf490b8098d8e75f43cf5e
Operating System: Linux Mint 21.1 
Kernel: Linux 5.15.0-60-generic
Architecture: x86-64
Hardware Vendor: Intel_R_ Client Systems
Hardware Model: NUC6CAYH

To change the hostname using the hostnamectl command, do this:

sudo hostnamectl set-hostname new-hostname


/etc/hosts look for a line such the one below. Warning, do not change localhost. The localhost entry may be used and as convention localhost is always   localhost   old-hostname

You might also have a /etc/cloud/cloud.cfg file. If so, set the following entry:

preserve_hostname: true

In summary:

hostnamectl set-hostname new-hostname


See Also

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