use Time::Local;

my $string = "2004-08-07 13:22:21";
my $timestamp;
if ($string =~ /^ (\d{4}) \- (\d\d) \- (\d\d) \s+ (\d\d) \: (\d\d) \: (\d\d) $/x) {
  # ist hier die Reihenfolge ok? jahr-monat-tag ? oder ist es jahr-tag-monat?
  my ($year, $month, $day, $hour, $min, $sec) = ($1, $2, $3, $4, $5, $6);
  $month--; $year -= 1900;
  $timestamp = timelocal($sec, $min, $h, $day, $month-1, $year-1900);
}
print "TIMESTAMP: $timestamp" if defined $timestamp;