A third option -- slurp each stanza into memory at once, process that stanza, and then print.
If you are sure you won't have square brackets inside your stanza, you could even let perl do the slurping for you by setting the input record separator. E.G. something like (warning, untested code ahead which may need tweaking...): 
$/="[";
while(<>) {
  ($newprefix) = m{uri.*([^/]*)$}m;
  if ($newprefix) {
     # we won't match on the first line so it will print just "["
     print $newprefix," ";
  }
  print;
}

[download]
Note the use of the "m" modifier of the matching to allow $ to match the end of line in the middle of a string.
You could also be more prosaic, and read in line at a time, concatenating to a temporary variable, until you hit your new stanza leader, and do a similar process. (That would be cleaner, and more extensible/less hacky, too).
Good luck...

--JAS

In reply to Re: Need RegEx assistance by jsegal
in thread Need RegEx assistance by Anonymous Monk

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.