I've tried like owner, with all permissions enabled, and doesn't work even, that's the output for any user:

That's my server setup:

I've never needed or used that command, so I don't remember what it's supposed to do. If I wanted to see anyone's permissions, I just look in the file. It's easier. ;-) (In many cases, you'd be looking at hundreds of permission nodes too, on servers using Essentials, which has more than 400 on its own.)

You'll need zml to give you details.

What zml do yo refer? And ... It's not for server managing, I was thinking more about moderation or permission check, I mean, if a basic user ask to a moderator what permissions he has, the moderator should be able to check them and notify the user.

Of course when I manage my server I see the permissions and groups inside .yml file but operators/moderators haven't got that possibility.

The user can type /help and see all the commands available to them. The "permissions" are not likely to make any sense or be any help to them.

I was referring to permissions what a particular user has got. Eventually one moderator could want to check what permissions has a particular user o a particular group.

And as I said, most users will not understand anything if you tell them "You have permission.node.whatever." because that does not tell the user anything about the commands associated with that permission node. Nodes are strictly admin-side information and commands are user-side information.

That's all I can tell you, regardless of whether you accept that information or not.

Ok, anyway I've thought would be a implemented feature intentionally that is not working properly.

Thank you for the aclaration.