if [ -n "$DOCKER_MACHINE_DEFAULT" ]; then
    eval $(docker-machine env $DOCKER_MACHINE_DEFAULT)
fi

function docker_machine_use() {
    eval $(docker-machine env "$*")
}

if [ -n "$DOCKER_MACHINE_DEFAULT" ]; then
    docker_machine_use $DOCKER_MACHINE_DEFAULT
fi

alias dmu=docker_machine_use

Add function and alias for using a docker machine
zsh: Add function and alias for using a docker machine
