MAC 下 docker 报错 Cannot connect to the Docker daemon

[code]WangWilliamdeMacBook-Pro-3:~ wangwilliam$ docker ps -a
Cannot connect to the Docker daemon. Is the docker daemon running on this host?
WangWilliamdeMacBook-Pro-3:~ wangwilliam$ docker version
Client:
Version: 1.11.1
API version: 1.23
Go version: go1.5.4
Git commit: 5604cbe
Built: Tue Apr 26 23:44:17 2016
OS/Arch: darwin/amd64
Cannot connect to the Docker daemon. Is the docker daemon running on this host?[/code]
解决方案：
在shell中执行：
[code]eval "$(docker-machine env default)"[/code]