use strict;
use warnings;

my $dir = "/whatever";
my $time = time();
my ($sec, $min, $hour, $mday, $mon, $year, $wday, $yday, $isdst) =
						localtime($time);
my $btime = $time - $wday * 86400 - $hour * 3600 - $min * 60 - $sec;

if (!-e "$dir/$btime.mrk") {
    # process all records timestamped ($btime - 604799) to $btime
    # create file "$dir/$btime.mrk"
}