因后面会将操作系统从CentOS6.4升级到CentOS7，先试用下CentOS7。

1. 启动容器服务

   systemctl start  docker.service

2. 下载CentOS7 镜像
   1.  
      [root@wxtest1607 ~]# docker pull centos:7.2.1511
   2.  
      [root@wxtest1607 lixr]# docker images
   3.  
      REPOSITORY TAG IMAGE ID CREATED SIZE
   4.  
      centos 7.2.1511 686672a1d0cc 7 weeks ago 194.6 MB

   下载来源：https://hub.docker.com/

3. 登录docker中的CentOS7
   1.  
      docker run -ti 6866 /bin/bash
   2.  
      #6866 是 IMAGE ID 前四位数字-能区分出是哪个image即可
   3.  
      root@b4ad1d1c87da /]#
   4.  
      #登录成功，接下来就可以为所欲为啦。
4. 检查CentOS7系统
   1.  
      root@b4ad1d1c87da /]# uname -a
   2.  
      Linux b4ad1d1c87da 3.10.0-327.el7.x86_64 #1 SMP Thu Nov 19 22:10:57 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
   3.  
      [root@b4ad1d1c87da /]# cat /etc/redhat-release
   4.  
      CentOS Linux release 7.2.1511 (Core)
5. 退出后 再进入CentOS7
   1.  
      [root@wxtest1607 ~]# docker ps -a
   2.  
      CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
   3.  
      b4ad1d1c87da 6866 “/bin/bash” 12 seconds ago Up 9 seconds mad_swanson
   4.  
      drunk_hypatia
   5.  
      [root@wxtest1607 ~]# docker exec -ti b4ad /bin/bash
   6.  
      [root@b4ad1d1c87da /]#

   7.