The options which apply to the getsubids command are:
-g
-h
For example, to obtain the subordinate UIDs of the testuser:
$ getsubids testuser 0: testuser 100000 65536
This command output provides (in order from left to right) the list index, username, UID range start, and number of UIDs in range.
login.defs(5), newgidmap(1), newuidmap(1), subgid(5), subuid(5), useradd(8), userdel(8). usermod(8),