Install docker-machine executable from official (Automatically check the running system)

installDockerMachine.sh

#!/bin/sh 

# Extract the value for the key
function jsonValue() {
  KEY=$1
  num=$2
  awk -F"[,:}]" '{for(i=1;i<=NF;i++){if($i~/'$KEY'\042/){print $(i+1)}}}' | tr -d '"' | sed -n ${num}p
}

# Get the latest version name from github
VERSION=`curl -s -X GET https://api.github.com/repos/docker/machine/releases/latest | jsonValue name 1`
VERSION=`echo $VERSION` # trim the leading whitespaces
if [[ $VERSION =~ ^v* ]]; then
  echo "Latest version is $VERSION"
else  
  VERSION="v0.14.0"
  echo "Failed to get latest version name, remain $VERSION"
fi

# Directory to store the docker-machine executable
DIR="/usr/local/bin"
if [[ -d $1 ]]; then
  echo "Path changed from $DIR to $1"
  DIR=$1
fi
URL_PREFIX="https://github.com/docker/machine/releases/download"
URL_FILE="docker-machine-`uname -s`-`uname -m`"
FILE_NAME="docker-machine"

# Fix the docker-machine url_file and executable filename by running environment, such as Linux, Mac, Windows(Cygwin or Ming[git-bash])
UNAME=`uname -s`
case "${UNAME}" in
    Linux*)     machine=Linux;;
    Darwin*)    machine=Mac;;
    CYGWIN*)    
      machine=Cygwin
      URL_FILE="docker-machine-Windows-x86_64.exe"  
      DIR="$HOME/bin"
      FILE_NAME="docker-machine.exe"
      ;;
    MINGW*)     
      machine=MinGw
      URL_FILE="docker-machine-Windows-x86_64.exe"  
      DIR="$HOME/bin"
      FILE_NAME="docker-machine.exe"
      ;;
    *)          machine="UNKNOWN:${UNAME}"
esac
echo ${machine}

# The docker-machine executable filename
BIN="$DIR/$FILE_NAME"
echo "Execuable path is ${BIN}"

# Url for downloading
URL="$URL_PREFIX/$VERSION/$URL_FILE"
echo ${URL}
  
if [[ ! -d $DIR ]]; then mkdir -p $DIR; fi && \
  curl -L $URL >$BIN && \
  chmod +x $BIN

sh installDockerMachine.sh: install docker-machine to default path(/usr/local/bin for *nix and $HOME/bin for win)
sh installDockerMachine.sh [DIR]: install docker-machine to [DIR]