I would combine the already suggested named capture groups with interpolated regexes.

my $month = qr{(?<month>\w+)};
# ...etc
my $re_dn = qr{^$month (\d+) (\d{2}:\d{2}:\d{2}) .*: eth(\d): link dow
+n};
my $re_dn = qr{^$month (\d+) (\d{2}:\d{2}:\d{2}) .*: eth(\d): link up,
+ (\d+)Mbps, ([^,]+), lpa (\w+)};

[download]

also consider using the /x modifier for better readability.

if you are concerned about DRY and error avoidance, you can also use a pattern hash and automatically wrap the names later

# sketch, totally untested

# define groups
my %p = (
   month => '\w+',
   ...
);
 
# wrap named groups later
while ( my ($k,$v) = each %p ) {
   $v = qr{(?<$k>)$v};
}

# compose patterns
my $re_dn = qr{^$p{month} $p{day} ...};

[download]

on a side note: you can also chain elsif to avoid always writing next in every if block

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery

In reply to Re: scan, match and extract by LanX
in thread scan, match and extract by seismofish

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.