If the caller has appropriate privilege, the groupadd command shall create a new group named group. The group name shall be unique in the group database. If no gid is specified, groupadd shall create the new group with a unique group ID.
The groupadd command is a system administration utility, see Path For System Administration Utilities.
|-g gid [-o]|
The new group shall have group ID gid. If the -o option is not used, no other group shall have this group ID. The value of gid shall be non-negative.