---------------------------------centos6-------------------------------------
[root@centos6 ~]$ hostname # 查看当前的hostnmae
centos6.magedu.com
[root@centos6 ~]$ vim /etc/sysconfig/network # 编辑network文件修改hostname行（重启生效）
[root@centos6 ~]$ cat /etc/sysconfig/network # 检查修改
NETWORKING=yes
HOSTNAME=centos66.magedu.com
[root@centos6 ~]$ hostname centos66.magedu.com # 设置当前的hostname(立即生效）
[root@centos6 ~]$ vim /etc/hosts # 编辑hosts文件，给127.0.0.1添加hostname
[root@centos6 ~]$ cat /etc/hosts # 检查
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4 centos66.magedu.com
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6
---------------------------------centos7-------------------------------------
[root@centos7 ~]$ hostnamectl set-hostname centos77.magedu.com # 使用这个命令会立即生效且重启也生效
[root@centos7 ~]$ hostname # 查看下
centos77.magedu.com
[root@centos7 ~]$ vim /etc/hosts # 编辑下hosts文件， 给127.0.0.1添加hostname
[root@centos7 ~]$ cat /etc/hosts # 检查
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4 centos77.magedu.com
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6