54

I can't seem to change the hostname on my CentOS 6.5 host. I am following instructions I found on this (now defunct) page.

I set my /etc/hosts like so ...

    [root@mig-dev-006 ~]# cat /etc/hosts
    127.0.0.1   localhost localhost.localdomain
    192.168.32.128  ost-dev-00.domain.example ost-dev-00
    192.168.32.129  ost-dev-01.domain.example ost-dev-01

... then I make my /etc/sysconfig/network file like so ...

    [root@mig-dev-006 ~]# cat /etc/sysconfig/network
    NETWORKING=yes
    HOSTNAME=ost-dev-00.domain.example
    NTPSERVERARGS=iburst

... then I run hostname like so ...

    [root@mig-dev-006 ~]# hostname ost-dev-00.domain.example

... and then I run bash and all seems well ...

    [root@mig-dev-006 ~]# bash

... but when I restart my network the old hostname comes back:

    [root@ost-dev-00 ~]# /etc/init.d/network restart
    Shutting down interface eth0:  Device state: 3 (disconnected)
                                                               [  OK  ]
    Shutting down loopback interface:                          [  OK  ]
    Bringing up loopback interface:                            [  OK  ]
    Bringing up interface eth0:  Active connection state: activating
    Active connection path: /org/freedesktop/NetworkManager/ActiveConnection/6
    state: activated
    Connection activated
                                                               [  OK  ]
    [root@ost-dev-00 ~]# bash
    [root@mig-dev-006 ~]#
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8
  • 1
    Have you edited your /etc/hostname file?
    – Anthon
    Commented Jul 17, 2014 at 5:54
  • There isn't a /etc/hostname file. [root@smp-mig-dev-006 ~]# ls -l /etc/hostname outputs ls: cannot access /etc/hostname: No such file or directory
    – Red Cricket
    Commented Jul 17, 2014 at 5:56
  • Might be a Centos thing. What does your manpage tell you about the permanency of hostname somename, that it has a lasting effect? (if not why do you make that call?)
    – Anthon
    Commented Jul 17, 2014 at 5:59
  • 4
    I think /etc/hostname is in CentOS 7 but not in CentOS 6.
    – Pavel Šimerda
    Commented Jan 4, 2015 at 9:21
  • I realize this is old, but I smell NetworkManager at work, either that or you may have HOSTNAME= set in another file than network (ie, in network-scripts). The /etc/hostname file is not used in CentOS 6 (it's a systemd thing; that means CentOS 7 and up). Check the contents of the /etc/sysconfig/network-scripts/ifcfg-eth0 file; what is in it? Note: If you look at Redhat's if_post script in network-scripts/, you will see that set_hostname simply runs "hostname $HOSTNAME", where HOSTNAME is a shell variable set either in the network file or the ifcfg-eth0 file.
    – Mike S
    Commented Apr 30, 2015 at 18:12

7 Answers 7

Reset to default
74

to change the hostname permanently, you need to change it in two places:

vi /etc/sysconfig/network
NETWORKING=yes
HOSTNAME=newHostName

and: a good idea if you have any applications that need to resolve the IP of the hostname)

vi /etc/hosts 
127.0.0.1 newHostName
127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6

and then

 rebooting the system
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9
  • 7
    At the end of this two changes add hostname newHostName, is not necessary to reboot I think
    – evalarezo
    Commented Sep 19, 2014 at 21:01
  • 4
    Editing the /etc/hosts file does not seem to be required
    – jgritty
    Commented Dec 12, 2014 at 21:09
  • 2
    The answer has been accepted, but first, /etc/hosts change is there only to make the hostname resolvable, not to change it, and /etc/sysconfig/network looks the same as in OP. Can anyone explain what exactly OP needed to change to make it work?
    – Pavel Šimerda
    Commented Jan 4, 2015 at 9:24
  • 3
    I think a correct answer should work as an answer to the question. Repeating data from the question is good as long as the answer says the OP configured it correctly but didn't perform actions needed to load the new configuration (e.g. reboot).
    – Pavel Šimerda
    Commented Jan 4, 2015 at 12:46
  • 2
    Reboot not necessary. Check strace -f hostname blah . The kernel gets the message right away. /etc/hosts does not affect the host's hostname, in CentOS 6.5 (and 7) at least. And this answer is incorrect in that it's missing the hostname command which is what informs the kernel of its host's name.
    – Mike S
    Commented Apr 30, 2015 at 18:56
20

You can change your hostname with a single command.

  • Command: hostname - this displays old hostname
  • Command: hostname <new name> -this sets new hostname

Example

$ hostname mynewhost

For persisting the new hostname across reboot

edit /etc/sysconfig/network file to look like below

NETWORKING=yes
HOSTNAME=myhostanme

For video help

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3
  • I believe this is the most correct answer. Worth adding that running: man hostname; shows more options for setting pretty, transient, static etc.
    – ekerner
    Commented Jul 11, 2016 at 11:55
  • I think it is not enough to be persistent at reboot. You need to also modify /etc/sysconfig/network file.
    – timothepoznanski
    Commented Mar 1, 2017 at 12:58
  • Thank you, you saved me :)
    – Hien Nguyen
    Commented Jan 15, 2021 at 9:33
6

Apart from the answers already provided for CentOS 6.5,

CentOS 7 also has a text based user interface tool to change hostname (and other network settings), part of Network Manager:

nmtui

starts this user interface:

enter image description here

which has an option to Set system hostname.

The text user interface of NetworkManager is installed by default in CentOS-7-x86_64-DVD-1511.iso image, base install. If yours doesn't have it, you can install it with the following command:

yum install NetworkManager-tui
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4

No reboot is required for changing hostname on CentOS 6.5.

The following command informs the kernel of the new hostname :

# hostname new_hostname

The following command so that the hostname be persistent across reboot :

# sed -i "s/^HOSTNAME=.*/HOSTNAME=new_hostname/g" /etc/sysconfig/network
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2

I had to do this for a bunch of machines. Here is a simple python script to help you out. Simply provide the name of the new host as the first argument to the script.

for example: if you name the script changeHost.py then run it as

changeHost.py [NewHostName]

where NewHostName is your desired host name.

Also make sure to run this script as root.



#!/usr/bin/env python
import os

from sys import argv
script, newHostName = argv

print "Modifying network file..."
target = open("/etc/sysconfig/network","w")
target.truncate()
target.write("NETWORKING=yes\n")
target.write("HOSTNAME=")
target.write(newHostName)
target.write("\n")
target.close()

print "Modifying hosts file..."
target = open("/etc/hosts","w")
target.truncate()
target.write("127.0.0.1 ")
target.write(newHostName)
target.write(" localhost.localdomain localhosts\n")
target.close()

print "Set new hostname to %r" % newHostName
os.system('/bin/hostname ' + newHostName)
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3
  • 2
    Hmm that's an ugly script. I wonder if Puppet would be a better tool for dealing with hostname.
    – Red Cricket
    Commented Jan 4, 2015 at 7:32
  • 2
    docs.ansible.com/hostname_module.html
    – jgritty
    Commented Jan 15, 2015 at 6:31
  • 4
    This script is about 3 times as long as it needs to be. Python is the wrong tool for the job. A bash script would be much shorter, more readable, and more maintainable.
    – Mike S
    Commented Apr 30, 2015 at 18:59
1

If you are on the Centos 7.x. Insert the following command. 

nmtui

It will have an option of set system hostname. Press Enter on it.

Write your hostname.

Click Ok.

Now, check with command hostname.

It will have your saved hostname.

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2
0

Unfortunately I was not able to change the hostname by making entries in:

/etc/sysconfig/network

and

/etc/hosts file

However I was able to change the hostname by editing the file below:

vi /etc/hostname
server01

Restart and test hostname by:

hostname
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1
  • 3
    Note the comment on the OP stating that /etc/hostname exists in CentOS 7, but not CentOS 6
    – Fox
    Commented Mar 17, 2017 at 22:46

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