rgroup_name
if (rgroup_name(g->gl_statv[i]->st_gid) != NULL)
if (rgroup_name((gid_t)(d[i]->a.gid)) != NULL)
const char *rgroup_name(uid_t gid);
rgroup_name(g.gl_statv[i]->st_gid));
rgroup_name(sb.st_gid));