and the next thing is the hostname.

Permanent hostname change on RedHat based systems

RedHat based system use the file /etc/sysconfig/network to read the saved hostname at system boot. This is set using the init script /etc/rc.d/rc.sysinit

/etc/sysconfig/network
NETWORKING=yes
HOSTNAME=”plain.domainname.com”
GATEWAY=”192.168.0.1?
GATEWAYDEV=”eth0?
FORWARD_IPV4=”yes”

So in order to preserve your change on system reboot edit this file and enter the appropriate name using the HOSTNAME variable. Use sysctl to change the hostname

Why would someone need a different method of doing the same thing as above? No idea, but here is anyway: use sysctl to change the variable kernel.hostname: Use:

sysctl kernel.hostname

to read the current hostname, and

sysctl kernel.hostname=NEW_HOSTNAME

to change it.