If you forget to set your correct hostname / domainname at your linux installation then you can easily fix it if you follow the next steps from this “tutorial”. Changing hostname/domainname is easy but first you will need to know what kind of linux distribution do you run: Debian or RedHat based. I will try to enumerate the most common distributions based on Debian and RedHat to help you find the roots of yours distribution.

Debian based distributions:
* Collax
* Damn Small Linux
* Debian JP
* Embedded Debian
* Euronode
* Floppix
* Gibraltar
* GNUstep LIVE CD
* Kanotix
* KNOPPIX
* Linspire
* Linex
* MEPIS
* M.N.I.S
* Morphix
* RAYS LX
* Stonegate
* Ubuntu, Kubuntu, Xubuntu
* Xandros

RedHat based distributions:
* Asianux
* CentOS
* ClarkConnect
* Scientific Linux
* SME Server
* White Box Enterprise Linux
* Cobalt RaQ4
* DomaTes Linux

Changing permanently the hostname / domainname on linux distributions based on RedHat:

1. You can use redhat-config-network GUI tool. Just go to DNS tab > Setup hostname and domain name. After just save your config and you are done.
2. Or you can edit /etc/sysconfig/network and replace the value of HOSTNAME with your domain name.
Edit /etc/sysconfig/network

nano /etc/sysconfig/network

Replace HOSTANAME with your hostname:

HOSTNAME=home.randombugs.com

Changing permanently the hostname / domainname on linux distributions based on Debian:

Just edit /etc/hostname and replace or add your hostname there.
Edit /etc/hostname:

nano /etc/hostname

Replace/Add your hostname:

home.randombugs.com

To make your changes active just run in console:

/etc/init.d/hostname.sh restart

On ALL Linux system is recommended to change domainname and hostname in /etc/hosts and /etc/resolv.conf, because all have an influence to your network settings. Just look in above files after your old hostname/domainname and just replace it.

Changing the hostname / domainname on any linux distributions:

You can also change your hostname temporarily on any disitribution with hostname comand:

hostname home.randombugs.com

and this will remain until next reboot.

To change your hostname permanently on any distribution just edit /etc/sysctl.conf and add:

kernel.hostname=[hostname]

and to make your changes active just run:

sysctl -p

Good luck !