How to change hostname in Red Hat 6 ?

There are several ways to change the hostname of a machine running Redhat 6.  These also works on CentOS, Fedora and older/other Redhat variants.

First: The "hostname" command.

You can use the hostname command to see the current host name of the system.

# hostname

linux4freshers.com

You can also use the hostname command to change the host name of the machine.

# hostname linuxforfreshers.com

Then issue the hostname command again to see the changes.

# hostname

linuxforfreshers.com

This only makes a temporary or non-persistent change of hostname.

Second: The /etc/sysconfig/network configuration file. (preferred method)

In order for the change to survive a reboot, or to make it persistent, you must change it in the /etc/sysconfig/network-scripts/ifconfig-eth0 file.

Open the file in your favorite editor and change the following line to reflect your desired hostname.

HOSTNAME=linuxforfreshers.com

After making changing to the configuration file you need to restart the network service in order to read that file.

/etc/init.d/network restart

NOTE: Do not do this remotely (via ssh) or you will lose your connection.

If you issue the hostname command now, you will see the hostname has changed.

Third: The /proc/sys/kernel/hostname entry.

Another simple way to change the hostname is to echo the hostname into the /proc/sys/kernel/hostname file.

echo "linuxforfreshers.com" > /proc/sys/kernel/hostname

NOTE: Using the /etc/sysconfig/network file is the preferred method to set the permanent hostname of a system.  Anything in the /proc/sys/kernel/hostname file will be overridden by the /etc/sysconfig/network file during a reboot.