#!/usr/bin/perl
#
use strict;
use Data::Dumper;

my $test = { k4 => 1, k2 => 1, k3 => 1, k1 => 1};
my $first = 'k4';
my @list = map  { [$_->[0], ($_->[0] eq $first ? '' : $_->[0])] } 
 sort { $a->[1] cmp $b->[1] } 
 map  { [$_, ($_ eq $first ? '' : $_)] } 
 keys %$test;
print "Erg: " . Dumper(@list);