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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:

GATEWAY= #I do have a proper IP address here

My /etc/hosts file contains:       localhost.localdomain   localhost      localhost.companyname.com     localhost
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2 Answers 2

  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

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

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And some apps pull the host name at startup and not again. Rebooting is a good way to restart everything at once. –  McJeff May 7 '10 at 20:41
service --full-restart will accomplish that without a reboot, although at that point you might as well. –  Rodger May 7 '10 at 21:50

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

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