1 查看系统是否已安装Docker

[root@localhost ~]# yum list installed | grep docker

2 卸载Docker

[root@localhost ~]# yum remove -y 卸载的软件名

3 Docker安装,启动与停止

# 安装需求包
[root@localhost yum.repos.d]# yum install -y yum-utils device-mapper-persistent-data lvm2

# 安装stable标准库(官方库,两者选一个就行)
[root@localhost yum.repos.d]# yum-config-manager \
> --add-repo \
> https://download.docker.com/linux/centos/docker-ce.repo

# 安装stable标准库(阿里库,两者选一个就行)
[root@localhost yum.repos.d]# yum-config-manager \
--add-repo \
https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo

# 安装docker(ce为社区版--免费  se为企业版--收费)
[root@localhost ~]# yum install -y docker-ce

# 查看docker是否已安装
[root@localhost yum.repos.d]# yum list installed | grep docker
containerd.io.x86_64                 1.2.10-3.2.el7                 @docker-ce-stable
docker-ce.x86_64                     3:19.03.5-3.el7                @docker-ce-stable
docker-ce-cli.x86_64                 1:19.03.5-3.el7                @docker-ce-stable


# 查看docker版本
[root@localhost yum.repos.d]# docker -v
Docker version 19.03.5, build 633a0ea

# CentOS7 启动 Docker
[root@localhost ~]# systemctl start docker

# 查看docker状态
[root@localhost ~]# systemctl status docker
● docker.service - Docker Application Container Engine
   Loaded: loaded (/usr/lib/systemd/system/docker.service; disabled; vendor preset: disabled)
   Active: active (running) since 五 2020-01-03 14:29:10 CST; 51s ago
......


# 停止Docker
[root@localhost ~]# systemctl stop docker
[root@localhost ~]# systemctl status docker
● docker.service - Docker Application Container Engine
   Loaded: loaded (/usr/lib/systemd/system/docker.service; disabled; vendor preset: disabled)
   Active: inactive (dead) since 一 2020-01-06 16:21:42 CST; 1s ago
......


# 开机启动docker
[root@localhost ~]# systemctl enable docker
Created symlink from /etc/systemd/system/multi-user.target.wants/docker.service to /usr/lib/systemd/system/docker.service.

4 Docker 简单使用

# 下载centos:7 镜像
[root@localhost ~]# docker pull centos:7

# Docker 以 centos:7 镜像创建新容器,在容器里执行 bin/echo "Hello Docker",然后输出结果
[root@localhost ~]# docker run centos:7 /bin/echo "Hello Docker"
Hello Docker

参数解析：
    docker: Docker 的二进制执行文件
    run: 与前面的 docker 组合来运行一个容器
    centos:7 指定要运行的镜像,Docker 先从本地主机上查找镜像,不存在,Docker 从镜像仓库 Docker Hub 下载公共镜像
    /bin/echo "Hello Docker": 在启动的容器里执行的命令