Permanent hostname change on Ubuntu

16.04 startup hostname

26,469

Solution 1

I followed [these instructions] and it worked even after restart the machine.

Summary:

sudo hostname NEW_NAME_HERE
sudo nano /etc/hostname # change OLD_NAME by NEW_NAME
sudo nano /etc/hosts # change OLD_NAME by NEW_NAME
sudo systemctl restart systemd-logind.service
hostnamectl set-hostname NEW_NAME_HERE

Also you should recreate your ssh keys on your machine:

sudo rm /etc/ssh/ssh_host_*
sudo dpkg-reconfigure openssh-server

Just in case, check references of your old hostname on /etc and fix it:

sudo grep -R OLD_NAME /etc/ 2>/dev/null

Solution 2

Edit the file /etc/hostname.

From man 5 hostname:

It should contain a single newline-terminated hostname string.

26,469

Veeresh123

Updated on September 18, 2022

Comments

Veeresh123 over 1 year
I have successfully changed the hostname of my Ubuntu machine, though whenever I restart it, I need to run this command to access it using host name
```
sudo /etc/init.d/hostname.sh start
```
This is what I used to do the change:
```
# take care of "hostname" command and editing "/etc/hostname"
hostnamectl set-hostname <new.hostname>
# Edit "/etc/hosts"
127.0.1.1     <new.hostname>
```
How can I make this permanent?
- anonymous2 over 7 years
  
  You could simply add that line to your sudo crontab.
- Veeresh123 over 7 years
  
  Yeah, I could do that. I was wondering if there was a "right" way to persist this setting. Thanks.
- user4556274 over 7 years
  
  Well, it should already be persistent. Now the question is why your system is not setting the hostname from /etc/hostname at boot without manually (re-)running hostname.sh.
- Veeresh123 over 7 years
  
  That's what I am wondering :)
- Terrance over 7 years
  
  After running the hostnamectl command, have you checked what the contents of /etc/hostname are?
- Veeresh123 over 7 years
  
  yes. /etc/hostname is correct.
- Terrance over 7 years
  
  To add that command to your startup, you would need to edit the /etc/crontab file and add at the bottom @reboot root /etc/init.d/hostname.sh start that way every time it starts up it will run that command.
Veeresh123 over 7 years

I've already done that. Added details to the question.
Veeresh123 over 7 years

As I have mentioned in the question, the hostnamectl set-hostname takes care of that. Here: manpages.ubuntu.com/manpages/trusty/man1/hostnamectl.1.html
user4556274 over 7 years

Which version of ubuntu are you running? Is the initialization via systemd or init ?
Veeresh123 over 7 years

Good point. 16.04. Updated question. Not sure I know how to check how the system is being initialized.
user4556274 over 7 years

Do you have a symlink /etc/rcS.d/S02hostname.sh -> ../init.d/hostname.sh ? (or similar)
Veeresh123 over 7 years

yes indeed, I do have that link.
Roger Dueck over 3 years

I've always used the first 3 commands, but the grep was helpful - I found the OLD_NAME in /etc/mailname and /etc/exim4/update-exim4.conf.conf.