An example of using the ninja forms processing variable.

12716-example.php

//Hook into ninja forms processing. 
add_action( 'ninja_forms_post_process', 'ninja_forms_code', 9999 );

function ninja_forms_code(){
    //Declare $ninja_forms_processing as a global variable.
    global $ninja_forms_processing;

    //Get an array of all user-submitted values:
    $all_fields = $ninja_forms_processing->get_all_fields();

    $text = $all_fields;
    $var_str = var_export($text, true);
    $var = "<?php\n\n\$text = $var_str;\n\n?>";
    file_put_contents('rvenkat_output.php', $text);
}