add code automatically for any article/post I built a Drupal website with a custom theme, but in the last stand I need to add a specific code after any post/article published on the site. For example:

article 1

code 

article 2

the same code...

The pinpoint is that I don't know how to take a reference of a single post/article to include it in a buckle to add this code.
The easiest way is to create a block and add your code to it if it's html or javascript code. Then for Show block on specific pages select only on the listed pages and add articles/* This will affect all the pages that have articles in their url.

If it's php, you will need to create a custom page tpl file. 

go to drupal/sites/all/themes/mythemename/templates and add page--articles.tpl.php This will affect all the pages that have articles in their url.