The Drupal Path module matches only full URLs when creating SEO-friendly aliases. This module extends that behavior by also matching known sub-paths and replacing them with their respective alias.
For example, if user/1 is aliased to users/admin, this module rewrites the link to the user contact page user/1/contact to use the aliased URL users/admin/contact instead. This also includes Views URLs taking a node as argument (e.g. node/%/yourview), in short, every URL that is based on, or extends, an existing alias. In combination with the Pathauto module it is possible to get rid of all remaining exposed internal non-administrative URLs.
- While Sub-pathauto works when drupal_get_normal_path() is called, if drupal_get_path_alias() is called, the hook to alter URLs is not invoked. Functionality that uses this function to compare things like page visibility settings will not match the sub-path processed URL. This is due to core bug .
#D8CX: I pledge that Sub-pathauto will have a full Drupal 8 release on the day that Drupal 8 is released.