Users set up on OMV system have a UID and GID. When setting up NFS access to a share, one way to map the incoming user to the OMV user is to specify all connecting users to be anonymous and to specify the UID and GID to use for anonymous. Mmm...cannot use the literal name of an existing OMV user; it has to be the number! So, how do you find the UID and GID as numbers for an OMV user? (At least without guessing, or using SSH to remote connect to shell.)
Background:
Client UID =1000, GID=1000
On server (OMV) want effective user to be one defined in OMV, say Xyz (UID=1002, GID=1001).
So, the NFS share has the Extra Options as "subtree_check,secure,all_squash,anonuid=1002,anongid=1001".
(Security is lessened by using all_squash& anonuid & anongid, but at least the port is harder to get at than if I used 'insecure'.)