title: No such file or directory: 'geckodriver' for a simple Selenium application in Python
body: <p>I'm running a simple example of selenium on Linux:</p>
  
  <pre><code>from selenium import webdriver
  from selenium.webdriver.common.keys import Keys
  
  driver = webdriver.Firefox()
  driver.get("something")
  </code></pre>
  
  <p>and get an error:</p>
  
  <pre><code>FileNotFoundError: [Errno 2] No such file or directory: 'geckodriver'
  </code></pre>
  
  <p>How to fix it?</p>
  
  <pre><code>$ python
  Python 3.5.2 (default, Jun 28 2016, 08:46:01) 
  [GCC 6.1.1 20160602] on linux
  Type "help", "copyright", "credits" or "license" for more information.
  &gt;&gt;&gt; import selenium
  &gt;&gt;&gt; from selenium.webdriver.common.keys import Keys
  &gt;&gt;&gt; 
  </code></pre>