使用homebrew 分别安装docker,docker-machine,docker-compose.
1. brew install docker能够正确安装
2. brew install docker-machine报错，错误信息如下：
Error with pre-create check: "VBoxManage not found. Make sure VirtualBox is installed and VBoxManage is in the path"
解决办法：
从https://download.virtualbox.org/virtualbox/5.2.18/VirtualBox-5.2.18-124319-OSX.dmg下载virtualbox并手动安装；
执行命令：docker-machine create --driver virtualbox default
docker-machine env default
eval $(docker-machine env default)
3.都安装好之后，执行命令：docker search nginx，报如下错误：
Warning: failed to get default registry endpoint from daemon (Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?). Using system default: https://index.docker.io/v1/
Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?
解决办法：
a. 执行命令: docker-machine ls
b. 如果没有docker-machine列出来，则执行如下命令：
docker-machine create --driver virtualbox default
docker-machine env default
eval $(docker-machine env default)
c.如果有docker-machine列出，将列出的docker-machine作为默认值，执行如下命令：
docker-machine env 名称
eval $(docker-machine env 名称)
4. 执行docker-machine create --driver virtualbox default报错，错误信息如下：
Error creating machine: Error in driver during machine creation: /usr/local/bin/VBoxManage modifyvm default --firmware bios --bioslogofadein off --bioslogofadeout off --bioslogodisplaytime 0 --biosbootmenu disabled --ostype Linux26_64 --cpus 1 --memory 1024 --acpi on --ioapic on --rtcuseutc on --natdnshostresolver1 off --natdnsproxy1 on --cpuhotplug off --pae on --hpet on --hwvirtex on --nestedpaging on --largepages on --vtxvpid on --accelerate3d off --boot1 dvd failed:
VBoxManage: error: The machine 'default' is already locked for a session (or being unlocked)
VBoxManage: error: Details: code VBOX_E_INVALID_OBJECT_STATE (0x80bb0007), component MachineWrap, interface IMachine, callee nsISupports
VBoxManage: error: Context: "LockMachine(a->session, LockType_Write)" at line 529 of file VBoxManageModifyVM.cpp
解决办法：
执行命令：vboxmanage startvm default --type emergencystop
重新执行：docker-machine create --driver virtualbox default问题解决
问题解决