How to change host name in CentOS

# cat /etc/hosts
127.0.0.1               localhost.localdomain localhost
::1             localhost6.localdomain6 localhost6

# cat /etc/sysconfig/network
NETWORKING=yes
NETWORKING_IPV6=no
HOSTNAME=localhost
NTPSERVERARGS=iburst

# hostname
localhost.localdomain

just edit following method

# vi /etc/hosts
127.0.0.1               changename
::1             localhost6.localdomain6 localhost6


# vi /etc/sysconfig/network
HOSTNAME=CHANGENAME


#reboot

now you can get the changed name

in case fo EC2

#hostnamectl set-hostname yourhostname

# vi /etc/cloud/cloud.cfg
//add following line to bottom of the file

preserve_hostname: true

#reboot

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for centos 7

[root@localhost ~]# hostnamectl status
   Static hostname: localhost.localdomain
         Icon name: computer-vm
           Chassis: vm
        Machine ID: 6c426b1abe1c4ab8996398e6dff1cd7a
           Boot ID: 6a5cc86cdf224ff288b1646eb90c8747
    Virtualization: vmware
  Operating System: CentOS Linux 7 (Core)
       CPE OS Name: cpe:/o:centos:centos:7
            Kernel: Linux 3.10.0-514.el7.x86_64
      Architecture: x86-64

or 

#hostnamectl

[root@localhost ~]# hostnamectl set-hostname server.xxxxx.com

or else

go to #nmtui

and set the hostname

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# hostname --fqdn

rhel8_1.boobi.com

# hostname

rhel8_1.boobi.com

# dnsdomainname

boobi.com

# cat /etc/hosts

127.0.0.1   rhel8_1.boobi.com   rhel8_1

#cat /etc/hostname

rhel8_1.boobi.com

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