@section @code{getgroups}
@findex getgroups
-POSIX specification: @url{http://www.opengroup.org/onlinepubs/9699919799/functions/getgroups.html}
+POSIX specification:@* @url{http://www.opengroup.org/onlinepubs/9699919799/functions/getgroups.html}
Gnulib module: getgroups
@item
On Ultrix 4.3, @code{getgroups (0, NULL)} always fails. See macro
@samp{AC_FUNC_GETGROUPS}.
+@item
+On very old systems, this function operated on an array of @samp{int},
+even though that was a different size than an array of @samp{gid_t}.
@end itemize
Portability problems not fixed by Gnulib:
@itemize
+@item
+It is unspecified whether the effective group id will be included in
+the returned list, nor whether the list will be sorted in any
+particular order. For that matter, some platforms include the
+effective group id twice, if it is also a member of the current
+supplemental group ids.
@end itemize