Using chown to change the group owner of a directory is not permitted....Why?

First, use the chgrp command instead of chown and that will work.

In the case of using chown, for security reasons in most Linux contexts, any ownership change is restricted to the root user even though you are marked as the owner of the file, directory, etc or not. In one case, this is to prevent users from evading quotas by setting the file permission bits to 777 and changing the ownership of a file to some other unknown user and eating up their quota.

So using the chown command in a user context, especially where the ownership is not changing should not be used just to change the group of a file.

NOTE: You must be a member of the group you are attempting to change the file to. This can be verified by id -a. If you are not in the group, you will get this message eventhough you are the owner of the file.

You have to be part of the group in order to be able to change the current group ownership to . You can edit /etc/groups file as root to make sure that user justin is a part of nginx group. After making changes for the group, you need to relogin to the system to make it in affect or to change to the group without a restart/logout, you can use cmd newgrp nginx.

Now you should be able to change the group of the file or folder with cmd chgrp nginx test as user justin.