Changing hostname – The UNIX way!

While the /etc/hosts file is generally the first to come to mind when you think about changing the name of a Unix system, modifying this file is only one step in the process. The other files that need to be changed depend on which particular version of “*nix” you are running.

The following is a list of UNIX flavors and methods of changing hostname permanently on each system.

Solaris

On Solaris, there are three files that you need to edit. These include /etc/hosts, /etc/hostname. and /etc/nodename.

- Edit /etc/hosts with vi and update to the new hostname.
- Similarly update /etc/nodename using an editor or “echo newhost > /etc/nodename”
- Lastly, edit /etc/hostname.. The should be replaced by the name of the particular network interface on your server. For example, a common name is /etc/hostname.hme0. If you’re not sure about the interface name, simply do an ‘ifconfig -a’, this’ll display the network interface name.

Once you’ve updated the above 3 files, best thing is to reboot your system or if can’t reboot right away, you can execute ‘uname -S ‘ command to assign the new hostname immediately.

Redhat Linux (Fedora, Mandriva, PCLos)

On Redhat based Linux systems, the primary setting for the system hostname is included in the /etc/sysconfig/network file.

- Open this file in editor, you should see something like this:
—————————————————-
NETWORKING=yes
HOSTNAME=abc.example.com
—————————————————-
- and of course the /etc/hosts file.

Debian/Ubuntu Linux

Debian based systems use the file /etc/hostname to read the hostname of the system at boot time and set it up using the init script /etc/init.d/hostname.sh.

- Edit /etc/hostname and update to your new hostname, you can then run /etc/init.d/hostname.sh to activiate the change.
- Update your /etc/hosts file to refelect new hostname

You can also use sysctl to change the hostname:

- sysctl kernel.hostname (To read the current hostname)
- sysctl kernel.hostname=NEW_HOSTNAME (to change it)

To change in gui in Ubuntu you can click to:

- System > Administration > Networking > General tab > Host name field

Slackware Linux

Similar to Debian except the it is uppercase HOSTNAME.

- Edit /etc/HOSTNAME and update to new value
- Update /etc/hosts to new hostname value as well

SuSE Linux

To change hostname permanently on SuSE Linux

- Edit the file /etc/HOSTNAME and change the value in it, Save and exit
- Update /etc/hosts to new hostname value

Mac OSX

To change hostname on a Mac OSX server…

- Edit /etc/hostconfig and update to your new hostname
- And of course the /etc/hosts file needs to be adjusted to your new host

You can also execute the following command:

- sudo scutil –set HostName abc.example.com

OpenBSD

Very similar to Solaris operating system.

- Update to new hostname in /etc/hosts file
- Make appropriate change in /etc/myname
- Lastly, /etc/hostname.. Similar to Solaris, you’ll need to identify system interface and update this file appropriately.

HP-UX

The script /sbin/set_parms changes system parameters including hostname and IP address.

- /sbin/set_parms

Digital Unix

- Edit /etc/hostname.driver

- As well as /etc/hosts file

FreeBSD

To change hostname do:

- Edit /etc/rc.conf and update to new hostname value

- Edit /etc/hosts

AIX

AIX stores all its information in ODM (Object Database Manager) including hostname value. There are a couple ways of doing it:

- chdev -l inet0 -a hostname=thomas

Or you can use smitty as well.

NetBSD

- Edit /etc/myname

- And of course edit /etc/hosts file 

SCO Unix

I don’t know who in their right mind would run SCO these days. But anyhow the way to change hostname permanently is:

- sys-unconfig

IRIX

I can understand why IRIX may still be used. To change hostname:

- Edit /etc/sys_id and update to new host value

- Edit /etc/hosts as well

Then reboot your workstation/server for changes to take affect.

Finally, some general facts about all Linux distros. The following are commands that are unique to all flavors of Linux:

To print current system hostname on the system:

- hostname
- uname -n
- cat /etc/hosts | grep 127.0.0.1

To print the fully qualified domain name of the system:

- hostname -fqd

To temporarily update the system to new hostname:

- hostname new_hostname
- echo “new hostname” > /proc/sys/kernel/hostname

On most Linux flavors, you can also execute the command:

- netconfig