以这种方式启动了docker：
# service docker start
想要阻止它：
# service docker stop
可以＆＃39;吨。然后kill -9 ...所有正在运行的进程。
重新开始：
# service docker start
可以＆＃39; T：
Redirecting to /bin/systemctl start docker.service
Job for docker.service failed because the control process exited with error code. See "systemctl status docker.service" and "journalctl -xe" for details.
journalctl -xe日志：
-- The result is failed.
7月 11 21:17:16 centos75 systemd[1]: Unit docker.service entered failed state.
7月 11 21:17:16 centos75 systemd[1]: docker.service failed.
7月 11 21:17:16 centos75 polkitd[727]: Unregistered Authentication Agent for unix-process:12335:6759586 (system bus name :1.87, object path /org/freedesktop/PolicyKit1/AuthenticationAgent,
7月 11 21:17:43 centos75 polkitd[727]: Registered Authentication Agent for unix-process:12360:6762295 (system bus name :1.88 [/usr/bin/pkttyagent --notify-fd 5 --fallback], object path /org
7月 11 21:17:43 centos75 polkitd[727]: Unregistered Authentication Agent for unix-process:12360:6762295 (system bus name :1.88, object path /org/freedesktop/PolicyKit1/AuthenticationAgent,
7月 11 21:18:13 centos75 chronyd[732]: Source 121.111.253.121 replaced with 59.106.180.168
7月 11 21:19:07 centos75 polkitd[727]: Registered Authentication Agent for unix-process:12387:6770743 (system bus name :1.89 [/usr/bin/pkttyagent --notify-fd 5 --fallback], object path /org
7月 11 21:19:07 centos75 systemd[1]: Starting Docker Application Container Engine...
-- Subject: Unit docker.service has begun start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit docker.service has begun starting up.
7月 11 21:19:07 centos75 dockerd[12404]: time="2017-07-11T21:19:07.768545210-04:00" level=fatal msg="can't create unix socket /var/run/docker.sock: is a directory"
7月 11 21:19:07 centos75 systemd[1]: docker.service: main process exited, code=exited, status=1/FAILURE
7月 11 21:19:07 centos75 systemd[1]: Failed to start Docker Application Container Engine.
-- Subject: Unit docker.service has failed
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
运行docker ps返回：
Cannot connect to the Docker daemon. Is the docker daemon running on this host?
奇怪。