So I have to change the hostname on a server running Red Hat Enterprise Linux (v5). As I have to do this quite often I figured that I would note down where I need to change it.

• Update the HOSTNAME entry in /etc/sysconfig/network

• Update the entry in /etc/hosts to have the correct new hostnames both with domains and without.

• Update the list of hostnames that sendmail will accept emails for in /etc/mail/local-host-names.

• run hostname <NEW_HOSTNAME>

• This will update the hostname there and then, and avoids the need to restart the server to pick up the new hostname.

• Finally, if your server has DNS entries pointing to it update these to include the new hostname.

Well I have just figured out why some of the machines that I use had stopped picking up updates. When I look at the list of systems on the RedHat Network they had a list of updates that they hadn’t picked up but when I logged into the machines and ran

yum update

it said there were no updates. After trying a lot of things on one of the systems that I was free to test with I still couldn’t find out what was going on. Eventually I discovered that yum had corrupted it’s cache and so it thought that its list of packages was up to date when it wasn’t. The solution was quite easy after that

yum clean all

yum update

I know, I should have tried that at the start.