title: Pass Scrapy Spider a list of URLs to crawl via .txt file
body: <p>I'm a little new to Python and very new to Scrapy. </p>
  
  <p>I've set up a spider to crawl and extract all the information I need.  However, I need to pass a .txt file of URLs to the start_urls variable.</p>
  
  <p>For exmaple:</p>
  
  <pre><code>class LinkChecker(BaseSpider):
      name = 'linkchecker'
      start_urls = [] #Here I want the list to start crawling a list of urls from a text file a pass via the command line.
  </code></pre>
  
  <p>I've done a little bit of research and keep coming up empty handed.  I've seen this type of example (<a href="https://stackoverflow.com/questions/15611605/how-to-pass-a-user-defined-argument-in-scrapy-spider">How to pass a user defined argument in scrapy spider</a>), but I don't think that will work for a passing a text file.</p>