The following process works with all WordPress versions after version 3.7. There are several other options for enabling automatic background updates for WordPress including but not limited to: utilizing Jetpack with WordPress.com and utilizing WordPress plugins.
Turning on Automatic Background Updates causes WordPress to update whenever a new major or minor release is available. In some cases, a major or minor release may not work correctly with an installed plugin, which could cause your site to render improperly, or fail completely. It is very important that you have backups enabled, and that you monitor your site for problems closely. Enable Automatic Background Updates via wp-config.php
For a refresher on editing files with vim see: New User Tutorial: Overview of the Vim Text Editor
Navigate to your root WordPress directory (in this case: /home/example/public_html) and edit the wp-config.php file:
vim wp-config.php
or
vim /home/example/public_html/wp-config.php
Add the following to the file:
/* Enable Automatic Background Updates for WordPress Core */
define( ‘WP_AUTO_UPDATE_CORE’, true );
In this case, I added the above code just above:
/* That’s all, stop editing! Happy blogging. */
Then exit and save the file with the command :wq .