linux-hostname
hostname uname -n cat /proc/sys/kernel/hostname sysctl kernel.hostname
/etc/hosts
DEBIAN
nano /etc/hostname
then run sudo /etc/init.d/hostname.sh
SLACKWARE
nano /etc/hostname
as root hostname -F /etc/HOSTNAME
RED HAT / CENTOS /etc/sysconfig/network
hostname newname (or reboot)
FULLY QUALIFIED DOMAIN NAME (FQDN) hostname -f
nanon /etc/hosts
127.0.0.1 localhost xxx.yyy.zzz.aaa newname.domain.org newname
NOTE: after changing the hostname you should restart the X service