Where do you have problems? What did you try?

The general approach is simple:

• read the file line-by-line
• for each line, extract the date (e.g. by a regex)
• compare the date with your target-dates (Date::Calc has some handy functions for this, e.g. Delta_YMDHMS )
• process the fitting lines

• open the file
• while the file hasn't matched your final time
  • if you have matched your start time
    • push the line onto an array of interesting records
• Carry out any processing you need to do with the array of interesting records

In the documentation of Date::Calc, there is a recipe for just this question:

How do I check whether a given date lies within a certain range of dates?

use Date::Calc qw( Date_to_Days );

  $lower = Date_to_Days($year1,$month1,$day1);
  $upper = Date_to_Days($year2,$month2,$day2);

  $date = Date_to_Days($year,$month,$day);

  if (($date >= $lower) && ($date <= $upper))
  {
      # ok
  }
  else
  {
      # not ok
  }
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There are other modules like Date::Manip or Class::Date if you want alternatives, but it is sensible to use a module instead of "reinventing the wheel"

What part are you getting stuck on? Show us some code that shows us what you're doing, and tell us where you're having difficulty. We're not a coding service, after all.

You may want to read Ask questions the smart way, I know what I mean. Why don't you? and How (Not) To Ask A Question.

...roboticus

1. Read the file, line by line (if it's large) or into an array, if small enough to handle in RAM.
2. Test the data for your first condition.
3. When found, test the same data for your second condition.
4. If both are satisfied, write to new file, STDOUT or whatever
5. Repeat until the date-time is greater than your second condition.

This is not a code writing service.

So, based on the sequence of hints above, read the docs, write some code, and come back with specific questions about specific functions or operations if you get stuck.

How about using something like Apache::Parselog?

I searched for “Apache log” on CPAN and found a nice number of hits to interesting-looking packages.   I always strongly encourage folks to look first at CPAN before venturing any distance at all down any “primrose path.”

“Two paths diverged in a wood, and I ...
... found that CPAN had already been hundreds of times before down both of them.”

When comparing date/times you need to convert to something that can be compared. There are two basic options:
1. convert to epoch time (a huge binary number) and you use numeric compares on that number
2. convert to a text representation that allows you to use string compares.

Below I show method(2) because if you have any influence upon the format of this log file, this is a HUGE hint on what would be better!

A string like "2010-08-22 01:00:00" can be compared with string le,gt,cmp functions to "2010-08-21 06:00:00" without calling any Perl module or function. And it is "human readable" as opposed to an integer epoch time. Please note that leading zeroes are important in this type of format!

Below I just showed one way to do a format conversion like this. I didn't spend a billion hours making this as efficient as possible. Just trying to demonstrate the idea.

I think your "sort" was just wasted CPU MIP's. Write code that processes the file, use the reformat_date_time() subroutine to get the reformatted date/time for that line and look for lines that are gt or eq "2010-08-21 06:00:00" and lt or eq "2010-08-22 09:00:00" using string compare functions.

If was doing some huge sort, I would be tempted and probably would convert times to epoch values to speed up the compares in the sort. But here you are going to "touch" each input line exactly once to convert the date/time info into a better string, and then either save that line or not.

#!/usr/bin/perl -w
use strict;

my %month2numstring = (Jan => '01',
                       Feb => '02',
                       Mar => '03',
                       Apr => '04',
                       May => '05',
                       Jun => '06',
                       Jul => '06',
                       Aug => '08',
                       Sep => '09',
                       Oct => '10',
                       Nov => '11',
                       Dec => '12', );

while (<DATA>)
{
   my $datefield = (split)[3];
   my ($datestring) = $datefield=~ m|\[([\w/:]+)|;
   
   my $new_date_field = reformat_date_time($datestring);
   
   print "$new_date_field\n";
}

sub reformat_date_time
{
    my $date_time = shift;
   
    my ($date,$time) = m|([\w/]+):([\d:]+)|;
    my ($day,$month_text,$year) = split(m|/|,$date);
    
    $day = "0$1" if $day =~ m|^(\d)$|;      #force leading zero
    my $month = $month2numstring{$month_text};
    
    return ($year.'-'.$month.'-'.$day." $time");
}

=prints
2010-08-21 00:00:00
2010-08-21 00:01:00
2010-08-22 01:00:00
2010-08-22 02:00:00
2010-08-22 03:04:00
=cut

__DATA__
67.162.10.216   -       -       [21/Aug/2010:00:00:00   +0000]  GET /2
+010-08-18/news/ct-met-barrington-student-death-20100818_1_mental-illn
+ess-suicide-prevention-teen-suicides HTTP/1.1        200     6826 
67.162.10.216   -       -       [21/Aug/2010:00:01:00   +0000]  GET /2
+010-08-18/news/ct-met-barrington-student-death-20100818_1_mental-illn
+ess-suicide-prevention-teen-suicides HTTP/1.1        200     6826 
67.162.10.216   -       -       [22/Aug/2010:01:00:00   +0000]  GET /t
+racker.js.php?45aa01ed37b58d2a537b1ba12bb97fe2e5695a8c HTTP/1.1   200
+     2915
67.162.10.216   -       -       [22/Aug/2010:02:00:00   +0000]  GET /t
+racker.js.php?45aa01ed37b58d2a537b1ba12bb97fe2e5695a8c HTTP/1.1   200
+     2882
66.249.71.98    -       -       [22/Aug/2010:03:04:00   +0000]  GET /a
+d-openx.php?out=js&d=mod-top-hdr-defer&z-i=24809&z-n=top-...blah....
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