Having trouble writing to a file with PHP on Ubuntu

Question

I am running PHP 5.5.9 on Ubuntu 14.04. I'm having trouble writing to a file. I feel like this has to be a file permissions problem because I'm pretty sure the code is correct. The user that I'm logged in as has permissions to write in the folders that I am trying to write into, but I'm not sure if the localhost does. I'm not sure what the name of the localhost user is in order to use chmod. I tried using chmod 777 -R /var/www/html and the script is still is not able to write to my target folder, which has the path /var/www/html/Projects/MD_ScrapingTool/files. Here is my code:

$file = 'filetest.txt';
if($handle = fopen($file, 'w')) {
    $content = "123\n456";
    fwrite($handle, $content);
    fclose($handle);
} else {
    echo "Could not open file for writing.";
}

Answer 1

After some more research, I've got it figured out. Here is the solution for anyone having the same problem:

Since localhost belongs to the www-data group, I just added my user to that group.

sudo usermod -a -G www-data my_username

Then, I added the folder to the group.

sudo chgrp -R www-data /var/www

Then, I gave write permissions to the www-data group.

sudo chmod -R g+w /var/www

This worked for me without any other issue. Thanks!