I want to allow the _www group to write to a folder.
I clicked on the folder to go to the "Get Info".
At the bottom there is a "Sharing & Permissions" section with a "+" to add users. However it does not show any of the system groups such as _www.
Is there a way to enable showing hidden users and group in the GUI? Or do I have to do it via command-line instead? It seems the GUI allows to set permissions for several users and group, which I like, while the command I believe only allow 1 owner and 1 group?