For posterity,

Here's another approach that avoids loading the entire list in memory and also neglects the use of -M (it relies specifically on the naming convention of the candidate target files in OP's description).

hauxex points out some caveats using the -M file tests that could render its use unreliable. Gabor Szabo also highlights its weirdness.

Sharing the code below to illustrate the idea behind the computation of the psuedo_mtime field which was used for comparisons.

#!/usr/bin/perl
use strict;
use warnings FATAL => 'all';

use Getopt::Long qw ( :config no_ignore_case bundling );
use Pod::Usage   qw ( pod2usage );

# parse options
my (%opt,$dir);
GetOptions(\%opt, "help|h", "verbose|v", "test|t", "version", "directo
+ry|d=s" => \$dir) ||
    pod2usage(-verbose => 0);
pod2usage(-verbose => 1,  -exitval => 1) if $opt{'help'};
pod2usage(-verbose => 99, -exitval => 0, -sections => [qw(VERSION)]) i
+f $opt{'version'};
pod2usage(-verbose => 0,  -message => "$0: No directory given\n") if !
+$dir;

my @AGE_RATIONALISER = (31104000,2592000,86400,3600,60,1); # yy,mm,dd,
+hh,mm,ss converted to secs
my $processed_hash_ref;

opendir DH, $dir or die "Couldn't open directory $dir: $!";
chdir $dir;                     # filetests using relative path

while ($_ = readdir (DH)) {
    next unless -f $_ 
        && m/^\d_\d{4}_\d\d?_\d\d?_\d\d?_\d\d?_\d\d?_table/i;
    
    my @old_fname    = split /_/;
    my $new_fname    = join ('_', @old_fname[ 7..11 ]);
    my $psuedo_mtime = 0;       # divine a fake but consistent mtime f
+rom the filename
    $psuedo_mtime += $old_fname[$_+1] * $AGE_RATIONALISER[$_] for (0..
+$#AGE_RATIONALISER);

    # already seen a more recent file with the name we're
    # planning to use? skip current file
    next if defined $processed_hash_ref->{$new_fname} && 
        $processed_hash_ref->{$new_fname}->{AGE} > $psuedo_mtime;

    # file safe to be renamed... for now
    $processed_hash_ref->{$new_fname}->{OLDNAME} = $_;
    $processed_hash_ref->{$new_fname}->{AGE}     = $psuedo_mtime;
}
closedir DH;

# now proceed to rename items
map { 
    print "[!] rename $processed_hash_ref->{$_}->{OLDNAME} to $_\n" if
+ $opt{'verbose'};
    rename $processed_hash_ref->{$_}->{OLDNAME}, $_ unless $opt{'test'
+};
} keys %$processed_hash_ref;


__END__

=head1 NAME

=over 4

rename.pl - file renaming utility

=back

=head1 SYNOPSIS

=over 4

rename.pl [-t | --test] {-d log-file-directory}

rename.pl [-v | --verbose] {-d log-file-directory}

rename.pl [-h | --help]

rename.pl [--version]

=back

=head1 OPTIONS

=over 4

=item B<-t, --test>

Test run - no renaming takes place - effectively a simulation

=item B<-v, --verbose>

Verbose - printout of files to be renamed

=item B<-h, --help>

Help - prints this manual

=back

=head1 DESCRIPTION

B<This program> will read the given directory and rename a 
contingent of the files within said directory. Files to be
renamed that share the same target name - will have only 
the most recent one renamed.

=head1 AUTHORS

Shadowsong

=head1 VERSION

0.0.1-beta

=cut
[download]

---

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