#!/usr/bin/perl
use Date::Manip;
use Getopt::Long;

my ($from_text, $till_text);
GetOptions( from => \$from, till => \$till );

my $from_date = ParseDate($from_text);
unless ($from_date) {
  die "Invalid From date\n";
} 

my $till_date = ParseDate($till_text);
unless ($till_date) {
  die "Invalid till date\n";
}

unless (Date_Cmp($from_date,$till_date) > 0) {
  die "Horribly\n";
}

while(<>) {
  ... read the date ...
  if (Date_Cmp($date,$from_date) >= 0 and
      Date_Cmp($date,$till_date) <  0) {
    ... here we go ...
  }      
}