title: Add a line to top of csv file (first line) with PHP
body: <p>Need to process large csv files with php.
  Working with fgetcsv and performance seems pretty good. For even better/ faster processing I would like the csv files to have column names on the first row, which are missing right now.</p>
  
  <p>Now I would like to add a top row with columns names to the csv file with PHP before processing the files with fgetcsv. </p>
  
  <p>Is there a way to add a line top the top of the file with php easily? Or would this mean I have to take a approach like below?</p>
  
  <ol>
  <li>List item</li>
  <li>List item</li>
  <li>create a temp file </li>
  <li>add the column names to this temp file </li>
  <li>read original csv file contents </li>
  <li>put original csv contents into the temp file </li>
  <li>delete original file </li>
  <li>rename the temp file</li>
  </ol>
  
  <p>Any feedback on how to do this in the most effective way is highly appreciated. Thanks for your time :)</p>