Coincidentally, I am in the middle of working with gzipped logs myself. Perl, by itself, does not "understand" gzip files. You must make it understand by using Compress::Zlib or IO::Zlib. I prefer the latter, as it emulates the IO::* interface and makes your code a lot easier to work with. That said, you can do something like this: 
use strict;
use warnings;

use IO::Zlib; # also uses Compress::Zlib

my @hostnames = qw(baloo beast belle chip cogsworth lefou potts);
my $timestamp = $ARGV[0];
foreach my $host ( @hostnames ) {
  my $logpath = "/archive/$host/www/logs/access_log.$timestamp";
  my $fh = IO::Zlib->new($logpath, "r");
  die "Cannot open $logpath: $!" if !$fh;
# Probably good to check Compress::Zlib::gzerrno, too.
  while ( <$fh> ) {
    # do text processing here
  };
  $fh->close;
}

[download]
As for your third question, I'm not quite sure what you mean. I tend to use Date::Manip for all of my happy-fun date processing.

In reply to Re: parse gzipped weblogs by Kageneko
in thread parse gzipped weblogs by vili

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.