Redhat doesn't set my desired hostname on reboot

I have a redhat (EL5) server that I need to change the hostname on. I'm trying to put it back into a known state to help with server provisioning activities.

As part of changing the hostname, I'm updating /etc/sysconfig/network and /etc/hosts. I also have an explicit call to hostname. My desired state is that the server thinks its hostname is "localhost". And a call to "hostname" returns "localhost".

The problem I'm having is that when I reboot, the hostname is reverted to "localhost.companyname.com" which is not what I want. How do I ensure that the hostname is set up as just "localhost" when I reboot?

My /etc/sysconfig/network file contains:

NETWORKING=yes
HOSTNAME=localhost
GATEWAY=123.123.123.123 #I do have a proper IP address here

My /etc/hosts file contains:

127.0.0.1       localhost.localdomain   localhost
172.21.1.1      localhost.companyname.com     localhost

From serverfault $pageUsers[$entry.posts[0].author].name

• 1. Change the ^HOSTNAME line in /etc/sysconfig/network
  2. Change the hostname (FQDN and alias) in /etc/hosts
  3. Run /bin/hostname new_hostname for the hostname change to take effect immediately.
  4. Run /sbin/service syslog restart for syslog to log using the new hostname.

  A reboot is not required to change the system hostname, of course you should reboot in order to verify your issue is solved :)

  More information at http://kbase.redhat.com/faq/docs/DOC-8646

  NOTE:
  Your error is in the second line of /etc/hosts! just remove it.

  McJeff : And some apps pull the host name at startup and not again. Rebooting is a good way to restart everything at once.

  Rodger : service --full-restart will accomplish that without a reboot, although at that point you might as well.
  From AlberT

• Can't say that naming your server localhost is the wisest course of action.

  From Tux