报错内容：
docker无法启动报错start docker Failed at step EXEC spawning /usr/bin/containerd
找不到/usr/bin/dockerd文件
解决思路：
1、首先看一下二进制安装docker的路径/usr/local/bin
对于旧的docker启动文件进行删除
rm -rf /etc/systemd/system/devicemapper.conf
然后新添加docker.service
?cat >/etc/systemd/system/docker.service <<EOF
[Unit]
Description=Docker Application Container Engine
Documentation=http://docs.docker.io
[Service]
OOMScoreAdjust=-1000
Environment="PATH=/usr/local/bin:/bin:/sbin:/usr/bin:/usr/sbin"
ExecStart=/usr/local/bin/dockerd
ExecStartPost=/sbin/iptables -I FORWARD -s 0.0.0.0/0 -j ACCEPT
ExecReload=/bin/kill -s HUP \$MAINPID
Restart=on-failure
RestartSec=5
LimitNOFILE=infinity
LimitNPROC=infinity
LimitCORE=infinity
Delegate=yes
KillMode=process
[Install]
WantedBy=multi-user.target
EOF
systemctl daemon-reload
systemctl start docker
?