How do I change hostname under Linux operating system?

You need to use the hostname command. It is used to either set or display the current host or domain name of the system. The hostname is used by many of the networking programs (such as sendmail, Apache servers) to identify the machine.

Display Hostname

Type the following command:

hostname

Sample ouputs:

server.nixcraft.net.in

Step # 1: Change Hostname

You need to update two files:

1. Linux Distribution specific file. Edit appropriate file as per your distribution as follows.
2. /etc/hosts

Redhat / CentOS / Fedora: Change Hostname

Edit /etc/sysconfig/network, enter:

vi /etc/sysconfig/network

Set HOSTNAME=newhost.example.com, enter:

HOSTNAME=server2.nixcraft.com

Save and close the file. Type the following command:

hostname server2.nixcraft.com
hostname

Now, proceed to step # 2.

Debian / Ubuntu: Change Hostname

Edit, /etc/hostname file, enter:

vi /etc/hostname

Delete old name and add new name:

server2.nixcraft.com

Save and close the file. Type the following command:

hostname server2.nixcraft.com
hostname

Now, proceed to step # 2.

Slackware: Change Hostname

Edit /etc/HOSTNAME, enter:

vi /etc/HOSTNAME

Delete old name and add new one:

server2.nixcraft.com

Save and close the file. Type the following command:

hostname server2.nixcraft.com
hostname

Now, proceed to step # 2.

Suse / OpenSuse: Change Hostname

Edit /etc/HOSTNAME, enter:
Delete old name and add new one:

server2.nixcraft.com

Save and close the file. Type the following command:

hostname server2.nixcraft.com
hostname

Now, proceed to step # 2.

Step #2: Update /etc/hosts

Now, you need to edit /etc/hosts file, enteR:

vi /etc/hosts

Change all old hostname with newer one.