You want a hash indexed by the token you want to match. You might as well store the complete lines as the hash value. Then output the values which have more than one entry. (Untested) code: 
my %routes;
while (my $line = <>) {
  # Grab the route
  my ($key) = ($line =~ /^(\S+)\s/);
  # Make sure we have an array ref for this key
  $route{$key} ||= [];
  # And add this line
  push @{$route{$key}}, $line;
}

foreach my $value (values %routes) {
  if (@$values > 1) {
    print @$values;
    print "\n"; 
  }
}

[download]
Something like that anyway.

In reply to Re: Searching for two lines that begin with the same string by jbert
in thread Searching for two lines that begin with the same string by tgrossner

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.