Octave's group database functions return information in a structure with the following fields.
In the descriptions of the following functions, this data structure is referred to as a grp_struct.
Return an entry from the group database, opening it if necessary. Once the end of data has been reached,
Return the first entry from the group database with the group ID gid. If the group ID does not exist in the database,
Return the first entry from the group database with the group name name. If the group name does not exist in the database,
Return the internal pointer to the beginning of the group database.