#!/usr/bin/perl

# http://perlmonks.org/?node_id=1176809

use strict;
use warnings;

# sort by last number in each string

print map $_->[0], sort {$a->[-1] <=> $b->[-1]} map [$_, /\d+/g], <DAT
+A>;

__DATA__
this_5_string_12
some_12_garbage_23
this_5_string_8
17
this_5_string_23
some_12_garbage_6
102
this_5_string_19
5
this_5_string_101
[download]

prints:

5
some_12_garbage_6
this_5_string_8
this_5_string_12
17
this_5_string_19
some_12_garbage_23
this_5_string_23
this_5_string_101
102
[download]