use strict;
use warnings;

use Data::Dumper;

my @array = qw{abc def abc ghi ghi abc jklm abc def};

my %comb;
@comb{@array} = ();
my @uniq = sort keys %comb;

print Data::Dumper->Dumpxs([\@uniq], [qw{*uniq}]);

##</code><code>##

@uniq = (
          'abc',
          'def',
          'ghi',
          'jklm'
        );