title: Using command line to remove lines from text file
body: <p>I have a text file and need to remove all lines that DO NOT contain <code>http</code> in them.  Alternatively, it could just output all the files that DO contain <code>http</code> in them to the new file.</p>
  
  <p>The name of my original file is list.txt and I need to generate a new file with a name like new.txt</p>
  
  <p>I know that there are several ways to do this via command line, but what I'm really looking for is the quickest way since I need to do this with several files and each of them are a few gigs in size...</p>