Create a file on the fly using php output buffering. Sometime we need to create file on the fly this serves the purpose.

index.php

<?php

/*
 * @source http://stackoverflow.com/questions/15769732/write-to-php-output-buffer-and-then-download-csv-from-buffer
 */
$basic_info = fopen("php://output", 'w'); //Open output buffer to write
$content = file_get_contents(__FILE__); //Read the current file
fwrite($basic_info, $content); //Write to output buffer 
fclose($basic_info); // Close the context
header("Content-disposition: attachment; filename=index.php");
header("Content-Type: text/plain");