#!/usr/bin/perl -w

# requires GNU ls on your system.

@fnames=();
@fdates=();
if (!open(PH, "/bin/ls -l --time-style=+%y%m%d p[1-9abc][0-9]?????.[jm][po][gv]|")) {
    print(STDERR
	  "Rename olympus pnnnkkkk.jpg/.mov filenames to yymmdd-kkk format.\n".
	  "The file timestamp is used rather than the first 4 letters.\n");
}
while (<PH>) {
    @f = split(" ");
    push(@fnames, $f[6]);
    push(@fdates, $f[5]);
}

foreach $i (0..$#fnames) {
    $fn = $fnames[$i];
    $dt = $fdates[$i];
    $fn =~ m/^p.*?([^0]?...)\.(...)$/;
    $num = $1;
    $ext = $2;
    $nfn = "$dt-$num.$ext";
    chmod(0644, $fn);
    rename($fn, $nfn) || die("$fn -> $nfn: $!\n");
}