use strict;
use warnings;

my $SOME_DIR = '/home/scrat/scratchpad';
my $PATTERN = qr{
    \A
    \w+
    (\d\d\d\d_\d\d_\d\d_\d\d_\d\d_\d\d_\d\d\d)
    [\.\w]*
    \.xml
    \z
}xms;

opendir( DIR, $SOME_DIR ) || die "can't opendir $SOME_DIR: $!";

my @sorted = map  { $_->[0] }
             sort { $a->[1] cmp $b->[1] }
             map  { ($_ =~ $PATTERN) && [$_, $1] }
             grep { ($_ =~ $PATTERN) && -f "$SOME_DIR/$_"}
             readdir( DIR )
             ;
closedir DIR;

printf "%s\n", join "\n", @sorted;
[download]