if ( $) !~ /^$WANT_GID\b.*\b$WANT_GRP2\b/ ) {
	$) = "$WANT_GID $WANT_GRP2";
	die "Error: EGID change failed: $!"
		if $! || $) ne "$WANT_GID $WANT_GRP2";
}
warn "After: RUID=$<, EUID=$>, RGID=$(, EGID=$), umask="
	.sprintf("%o",umask)."\n";

##</code><code>##

use warnings;
use strict;

use User::pwent;
use User::grent;
use List::Util qw/any/;

my $u = $ENV{USER};
print " primary: ",
	getpwnam($u)->gid, "\n";
print "seconday: $_\n" for get_sec_grps($u);

sub get_sec_grps {
	my $user = shift;
	my @sec_grps;
	endgrent; # reset (?)
	while (my $g=getgrent) {
		push @sec_grps, $g->gid
			if any {$_ eq $user} @{$g->members};
	}
	endgrent;
	return @sec_grps;
}