title: Exporting spark dataframe to .csv with header and specific filename
body: <p>I am trying to export data from a spark dataframe to .csv file:</p>
  
  <pre><code>df.coalesce(1)\
    .write\
    .format("com.databricks.spark.csv")\
    .option("header", "true")\
    .save(output_path)
  </code></pre>
  
  <p>It is creating a file name "part-r-00001-512872f2-9b51-46c5-b0ee-31d626063571.csv"</p>
  
  <p>I want the filename to be "part-r-00000.csv" or "part-00000.csv"</p>
  
  <p>As the file is being created on AWS S3, I am limited in how I can use os.system commands. </p>
  
  <p>How can I set the file name while keeping the header in the file?</p>
  
  <p>Thanks!</p>