title: saveAsTextFile method in spark
body: <p>In my project, I have three input files and make the file names as args(0) to args(2), I also have a output filename as args(3), in the source code, I use</p>
  
  <pre><code>val sc = new SparkContext()
  var log = sc.textFile(args(0))
  for(i &lt;- 1 until args.size - 1) log = log.union(sc.textFile(args(i)))
  </code></pre>
  
  <p>I do nothing to the log but save it as a text file by using</p>
  
  <pre><code>log.coalesce(1, true).saveAsTextFile(args(args.size - 1))
  </code></pre>
  
  <p>but it still save to 3 file as part-00000、part-00001、part-00002, So is there any way that I can save the three input files to an output file?</p>