How to change the hostname of a Linux system

How to change the hostname of a Linux system


Normally we will set the hostname of a system during the installation process.
But we can change the hostname of the server in the following ways.

Change the hostname on a running system

For Linux systems you can change its hostname with the command ‘hostname'.

$hostname

The command 'hostname' without any parameter will output the current hostname of the system.

$hostname --fqd

The 'hostname' command with the above mentioned arguments will output the fully qualified domain name.

$hostname new_server

This will reassign the current hostname of the server as 'new_server'. This hostname will remain
in the server until the next reboot.

Permanent hostname change

For Redhat based distros:
RedHat based system use the file /etc/sysconfig/network to read the hostname at time of
system boot up. This is set using the init script /etc/rc.d/rc.sysinit

So edit this file and give the required name for the HOSTNAME variable in order to preserve the
hostname at startup. Please make sure that the hostname which we have entered should be a fully
qualified domain name (FQDN).

For Debian based distros:
Debian based systems use the file /etc/hostname to read the hostname of the system at boot up time.
The init script used here is /etc/init.d/hostname.sh

Edit the file /etc/hostname and change the name of the system and then run the script

/etc/init.d/hostname.sh start

This will make the change active and will preserve even in system reboot.