首先下载Chrome Driver（Firefox Driver的安装与该步骤相同）。
链接：
http://chromedriver.storage.googleapis.com/index.html
接下来在控制台（terminal）上操作一下红色字体的指令：
Install Unzip
sudo apt-get install unzip
Assuming you’re running a 64-bit OS, download the latest version of chromedriver from their website（http://chromedriver.storage.googleapis.com/index.html）
wget -N http://chromedriver.storage.googleapis.com/2.10/chromedriver_linux64.zip -P ~/Downloads
unzip ~/Downloads/chromedriver_linux64.zip -d ~/Downloads
Make the file you downloaded executable, and move it to /usr/local/share
chmod +x ~/Downloads/chromedriver
sudo mv -f ~/Downloads/chromedriver /usr/local/share/chromedriver
Also, create symlinks to the chromedriver. Cucumber would look for the drivers in /usr/bin/chromedriver
sudo ln -s /usr/local/share/chromedriver /usr/local/bin/chromedriver
sudo ln -s /usr/local/share/chromedriver /usr/bin/chromedriver