use Time::Local;
    my ($year, $month, $day) = qw(2002 02 21);
    my $gmtime = timegm(0,0,0,$day,$month-1,$year-1900);
    my @gmtime = gmtime($gmtime); # convert back
    print "day of week is $gmtime[6]\n"; # sunday = 0, saturday = 6
    my ($day_of_week) = gmtime($gmtime) =~ /^(\S+)/; # fetch first word
    print "day of week is $day_of_week\n"; # "Sun" .. "Sat"