我也有同样的问题。在CentOS 6.5中:

ps aux |grep `cat /var/run/docker.pid`

如果它显示不存在Docker守护进程，那么我输入:

docker -d

然后按Ctrl + D停止Docker。因为我们使用了-d选项，Docker将作为守护进程运行。现在我们可以做:

service docker start

然后我就可以做个分角。这是所有。

注意:如果这些不工作，你可以尝试yum更新，然后再重复这些，因为我yum安装在这些之前。

尝试将当前用户添加到docker组:

sudo usermod -aG docker $USER

然后注销并重新登录。

如果你使用gitlab-ci / gitlab-runners，如果你没有访问/var/run/docker.sock的权限，你就会得到这个错误。

Got permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock

解决问题:

sudo usermod -aG docker gitlab-runner

验证:

sudo -u gitlab-runner -H docker info

希望这能有所帮助。

在2020年4月的MacOS Catalina上，你只需要打开桌面应用程序:

I also had the same issue. The problem was in sockets allocated to docker-daemon and docker-client. First, permission was not set for the docker-client on docker.sock You can set it using "sudo usermod -aG docker $USER" Then check your bash file where the docker-client is running, For me it was on 0.0.0.0:2375, while docker-daemon was running on unix socket.(It was set in the configuration file of dockerd). Just comment the bash-line and it'll work fine. But if you want to make it work on TCP port instead of unix socket, change the configuration file of dockerd and set it on 0.0.0.0.2375 and keep the line in bash as it is if present or set it to 0.0.0.0:2375.

我在安装后重新启动Docker:

$ sudo service docker stop
$ sudo service docker start

这很有效。