use warnings;
use strict;

my $str = "x.z.y";
my ($first, $second) = $str =~ /(.+)\.([^.]+)$/;
print "$first,$second\n";

__END__

x.z,y
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Good point. Thanks!

Use a lookahead:

print split '\.(?=[^.]*$)', $_ for 'x.y', 'x.y.z';;
x y
x.y z
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Why is this only returning x.z in $first and nothing in $second?

If the PATTERN contains capturing groups, then for each separator, an additional field is produced for each substring captured by a group (in the order in which the groups are specified

my $str = "x.z.y";
my ($first,$second) = split(/\.([^.]*)$/,$str);
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Or do, :P

sub split_it_this_a_way {
    my $string = shift || die "die, die, kill you all!";
    my ( $second, $first ) = split '\.', reverse($string), 2;
    ( ~~reverse($first), $second );
}

my $str = "x.z.y";
print $str, " -> ", join(" + ", split_it_this_a_way($str)), $/;
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...because that's, uh, easier... uh, to, uh...

($x, $y) = /(.*)\.(.*)/;
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I'd prefer bart's greedy match. But if you want splitting, then split, pop, rejoin:

use strict;
use warnings;

my $string = "x.y.z";
my @pieces = split /\./, $string;
my $last = pop @pieces;
my $first = join ".", @pieces;

print "$first $last\n";
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