I work with attachments (
C-c C-a) in Emacs Org Mode.
I configured the variable
org-file-apps to open pdf with the default PDF Viewer of my OS (in my case evince in Ubuntu 18.04), when I use the key binding
C-c C-a o (instead of
C-c C-a **O** to force emacs to open it in emacs).
I want the same for directories, but I don't know how to configure the variable
org-file-apps to start nautilus with the desired directory.