#!/usr/bin/perl

use strict;
use warnings;

use Tie::File;
tie my @tied_array, 'Tie::File', 'tiefile'  or die "Could not tie to tiefile: $!";

push(@tied_array, $_) for (1..3);

print "\@tied_array has " . scalar @tied_array . " elements before sorting\n";
@tied_array = sort {uc($a) cmp uc($b)} @tied_array;
print "\@tied_array has " . scalar @tied_array . " elements after sorting\n";
untie @tied_array;

##</code><code>##

~/dev/perl$ perl test_tie_file.pl
@tied_array has 3 elements before sorting
@tied_array has 4 elements after sorting
~/dev/perl$ perl test_tie_file.pl
@tied_array has 7 elements before sorting
@tied_array has 8 elements after sorting
~/dev/perl$ perl test_tie_file.pl
@tied_array has 11 elements before sorting
@tied_array has 12 elements after sorting
~/dev/perl$ cat tiefile


1
1
1
2
2
2
3
3
3

~/dev/perl$