johngg@shiraz:~/perl/Monks > perl -Mstrict -Mwarnings -E '
my @data = qw{
   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
   };
my $width = 50;

say for
   map { substr $_, 54 }
   sort
   map { do {
            m{(.*\D)?(\d+)$};
            pack qq{A${width}NA*}, ( $1 ? $1 : qq{\x7f} x $width ), $2, $_;
            }
       }
   @data;'
some_12_garbage_6
some_12_garbage_23
this_5_string_8
this_5_string_12
this_5_string_19
this_5_string_23
this_5_string_101
5
17
102