my $confs = '...';

##</code><code>##

my @array1 = (1, 2, 3);
my @array2 = '1, 2, 3';

##</code><code>##

my (@array1, @array2);
my $elements_for_array = '1, 2, 3';
push @array1, 1, 2, 3;             # @array1 has three elements
push @array2, $elements_for_array;  # @array2 has one element

##</code><code>##

#!/usr/bin/env perl -l

use strict;
use warnings;

my @filenames = qw{
    MOLEC8-B040-OPT-FREQ2.gout
    MOLEC1-B001-OPT-FREQ2.gout
    MOLEC2-B010-OPT-FREQ2.gout
    MOLEC10-B002-OPT-FREQ2.gout
};

my $re = qr{^[^-]+-([^-]+)};

my @sorted = sort { ($b =~ /$re/)[0] cmp ($a =~ /$re/)[0] } @filenames;

print 'Original filenames:';
print for @filenames;

print 'Sorted filenames:';
print for @sorted;

##</code><code>##

Original filenames:
MOLEC8-B040-OPT-FREQ2.gout
MOLEC1-B001-OPT-FREQ2.gout
MOLEC2-B010-OPT-FREQ2.gout
MOLEC10-B002-OPT-FREQ2.gout
Sorted filenames:
MOLEC8-B040-OPT-FREQ2.gout
MOLEC2-B010-OPT-FREQ2.gout
MOLEC10-B002-OPT-FREQ2.gout
MOLEC1-B001-OPT-FREQ2.gout